He was born in Amdur, Grodno district, Russian Poland.  His father was a Hebrew teacher and an “official rabbi.”  Until age fourteen he studied in religious elementary school, in synagogue study hall with recluses there devoted to Torah study, and in the Ruzhany Yeshiva; he later turned his attention to secular education and moved (1909) to Warsaw to prepare for the school examinations as an external student.  At that time he drew close to the Zionist socialists and was a regular visitor at the home of Y. L. Perets who befriended him.  In 1913 he was admitted into the Russian military and was sent to serve in Zhitomir, and from there in August 1914 he was sent to the front in Galicia, was wounded in a battle by the San River, and was provisionally released from service; he then returned to his hometown which was subsequently occupied by the German army.  In 1916 he settled in Grodno, became friends there with the poet Leyb Neydus (whose biography Zak would later write and publish in Neydus’s Bukh fun poemes [Book of poems]).  In late 1919 he returned to Warsaw and for many years became a member of the management committee of the Warsaw Jewish Literary Association and the Jewish section of the General Journalists’ Syndicate of Poland.  With the outbreak of WWII (September 1939), he remained in Warsaw before escaping in December and settling in Soviet-occupied Grodno where he worked as a literary manager of a Yiddish theatrical group.  In July 1940, together with thousands of other Jewish refugees from Poland, he was arrested by the Russian N.K.V.D. (Narodnyi Komissariat Vnutrennikh Del or People’s Commissariat for Internal Affairs [security bureau]).  He was imprisoned for one year in Grodno and then deported to a concentration camp in the Taiga of the distant north, in the polar zone; in August 1941 he was released as a former Polish citizen.  He went on to live in Kazakhstan, Turkmenistan, Uzbekistan, Tadzhikistan, and other Soviet Asian lands, and worked as an unskilled laborer, a night watchman, a water carrier, a shepherd on a collective farm, and other jobs of this sort.  With the repatriation of Polish refugees in April 1946, he returned to Poland and settled in Lodz.  For a time he served as secretary of the Yiddish Literary Association and the Yiddish Pen Club, and he gave lectures on the Polish Jewish region in Lower Silesia.  He left for Paris in 1948 and there became chairman of the union of writer-survivors, vice-president of Yiddish Pen Club, part of the management of the club “Tłomackie 13,” gave talks in Paris, the French hinterland, in London, and Brussels, and he visited Israel in 1950.  In 1952 he made his way to Buenos Aires, where he served as vice-chairman of the Yiddish Writers’ Union (named for H. D. Nomberg), a member of the executive of the Argentinian division of the World Jewish Culture Congress, and a delegate to the second world conference of the Culture Congress in New York in 1959.

He began his writing activities with an elegy, “Vos tsit mikh azoy tsu di viste mekadshim?” (What draws me to such a desert of blessings?), published in the weekly journal Der tog af shabes (Today, on the Sabbath) in Vilna (1908).  From that point he dedicated himself entirely to Yiddish literature and the press.  He contributed to Unzer lebn (Our life) in Warsaw (1910), in which he published (under the pseudonym “Even Yankev”) stories, poems, and feature pieces.  In 1912 he became editorial board secretary of the daily Der moment (The moment) in Warsaw.  Over the years 1915-1919, he placed pieces in the literary publications: Nyeman (Neman [River]), Unzer vinkl (Our corner [also serving as its editor]), and the half-Russian and half-Yiddish Unzer morgn-Nashe utro (Our morning)—in Grodno; and Letste nayes (Latest news) in Vilna.  In 1919 he became an internal contributor again to Warsaw’s Moment and, after the death of B. Karlinski, editor of the literary Friday supplement “People and Writings”; he also edited the last published number of the newspaper in besieged Warsaw (September 1939).  He was also a contributor to Moment’s midday newspaper Varshever radyo (Warsaw radio), in which he published translations from European literature and (using the pen name “Alfa”) was in charge of a column entitled “Gramen fun tog” (Rhymes of the day).  He published in installments, 1919-1920, “experiences of a man in a grey military coat among the multitudes, multitudes of grey military coats on the fields of eastern Galicia”; a year later it was published in book form as: Unter di fligl fun toyt (Beneath the wings of death), and it was reviewed very favorably by every Yiddish literary critic.  Over the course of his many years of literary activity, he published writings in: Varshever shriftn (Warsaw writings), Varshever almanakh(Warsaw almanac), Literarishe bleter (Literary leaves), Arbeter-tsaytung (Workers’ newspaper), Der veg (The way), Unzer veg (Our way), Vokhnshrift far literatur (Weekly writings for literature), Foroys (Onward), Yugnt-veker (Youth alarm), and Fraye yugnt(Early youth), among others—in Warsaw; Nayer folksblat (New people’s newspaper) andLodzer tageblat (Lodz daily newspaper)—in Lodz; Tog (Day) in Vilna; Dos naye lebn (The new life) in Bialystok; and, after WWII: Dos naye lebn, Yidishe shriftn (Yiddish writings),Unzer vort (Our word), Ikhud (Unity), Arbeter-vort (Workers’ word), Al hamishmar (On guard), and Lomir kinder lerner (Let’s study, children), among others—all in Poland; Unzer shtime (Our voice), Unzer vort (Our word), Arbeter-vort, Tsienistishe bleter (Zionist pages), Tsienistishe shtime (Zionist voice), Kiem (Existence), Frayland (Freeland), Kunst un visnshaft (Art and science)—in Paris; Forverts (Forward)—in which, among other items, he published his autobiographical work “Knekht zenen mir geven” (We were slaves)—andTsukunft (Future)—in New York; Idishe tsaytung (Jewish newspaper), Der holts-industryal(The wood industry), Ilustrirte literarishe bleter (Illustrated literary leaves), Grodner opklangen (Grodno echoes), and Der shpigl (The mirror), among others—in Buenos Aires; as well as in Yiddish newspapers and publications in the state of Israel.

In book form he published: Akordn (Chords), poetry (Grodno, 1918), 64 pp., second printing (Warsaw, 1921); Reges fun troym (Moments from dreams) (Warsaw, 1919), 32 pp.; Tsvishn fir vent, lider (Within four walls, poetry) (Warsaw, 1920), 188 pp.; Unter di fligl fun toyt (with twelve artistic images of Yankev Adler) (Warsaw, 1921), 225 pp.; In shotn, noveles (In the shadows, novellas) (Warsaw, 1922), 265 pp.; Di khurve un der palats (The destruction and the palace), a children’s story (Warsaw, 1923), 32 pp.; A zumer kholem un andere (A summer dream and others), stories (Warsaw, 1923), 174 pp.; Unter heymishe himlen, pyese in dray aktn (Under familiar skies, a play in three acts) (Warsaw, 1926), 104 pp.; Shtot-koshmarn, lider (City nightmares, poetry) (Warsaw, 1926), 80 pp.; Fonye ganef(Ruski thief), a chronicle from the Tsarist barracks (Warsaw, 1929), 130 pp.; Di froy un shtot, noveles (The woman and the city, novellas) (Warsaw, 1931), 160 pp.; Mit ash afn kop(With ash on the head), Holocaust poems (Lodz, 1947), 96 pp.; Yorn in vander, lider un poemen (Years wandering, poems) (Buenos Aires, 1949), 244 pp.; Tsvishn shotns, dertseylungen (Amid the shadows, stories) (Paris, 1950), 160 pp.; the trilogy “Di velt geyt unter” (The world turned upside down)—vol. 1: In umru fun yorn (Disquiet of years) (Buenos Aires, 1954), 388 pp., winner of the M. Stoliar Prize of 1954 given by Yidishe tsaytung in Buenos Aires; vol. 2: Knekht zenen mir geven, 2 volumes (Buenos Aires, 1956), recipient of the B. Suravich Prize from the World Jewish Culture Congress; vol. 3: Af shlyakhn fun hefker (Along the rough roads of lawlessness), 2 volumes (Buenos Aires, 1958), 685 pp., recipient of the Louis Lamed Prize of 1958.  He was also the author of a volume of poems on motifs taken from the Jewish Holocaust during WWII, Fun ale navenadn (From all the peregrinations) (Buenos Aires, 1955), 142 pp.  At the beginning of 1959 he began publishing a novel in Idishe zhurnal (Jewish journal) in Toronto: “Libe hintern ayzenem forhang” (Love behind the iron curtain).  Other book-length works include: Af fremder erd, lider un poemes (On alien terrain, poetry) (Buenos Aires: Kultur-kongres, 1962), 113 pp.; In onheyb fun a friling, kapitlekh zikhroynes (At the start of spring, chapters of memoirs) (Buenos Aires: Farband fun poylishe yidn, 1962), 322 pp.; Af vegn fun goyrl, dertseylungen (On the paths of destiny, stories) (Buenos Aires: Farband fun poylishe yidn, 1964), 220 pp.; In kinigraykh fun yidishn vort, eseyen un dermonungen (In the kingdom of the Yiddish word, essays and remembrances) (Buenos Aires: YIVO, 1966), 236 pp.; Fun heysn ash, lider un poemes (Of hot ash, poetry) (Buenos Aires: YIVO, 1967), 155 pp.; Geven a yidish poyln, eseyen un dermonungen (There was a Jewish Poland, essays and remembrances) (Buenos Aires, 1968), 279 pp.; Af shtile vegn, lider un poemes (On quiet pathways, poetry) (Buenos Aires: Kultur-kongres, 1971), 131 pp.; In opshayn fun doyres, eseyen un dermonungen (In the sight of the generations, essays and remembrances) (Buenos Aires, 1973), 280 pp.; Unter di fligl fun toyt; Fonye ganef (Tel Aviv, 1982).  He compiled: Khurbn, antologye (Holocaust, anthology) (Buenos Aires, 1970), 429 pp.; Pleytim tsvishn fayern (Survivors amid the fires) (Buenos Aires: YIVO, 1971), 301 pp.; Oysgevortslte un ayngevortslte, antologye (Uprooted and rooted, anthology) (Buenos Aires, 1971), 269 pp.

He translated works into Yiddish from Russian, German, and Polish: Mikhail Lermontov, Mtsiri (The novice [original: Mtsyri]), with a foreword by Noyekh Prilucki (Warsaw, 1921), 72 pp.; Nikolai Gogol, Di khasanim (The bridegrooms [original: Zhenit’ba[Marriage]), a comedy (Warsaw, 1922), 104 pp.; Max Nordau, Dos rekht af libe, pyese in fir aktn (The right to love, a play in four acts [original: Das Recht zu lieben]) (Warsaw, 1922), 125 pp.; August Strindberg, Der foter, drame in dray aktn (The father, a drama in three acts [original: Fadren]) (Warsaw, 1923), 104 pp.; Ivan Turgenev, Rudin, roman (Rudin, a novel) (Warsaw, 1923), second printing (Warsaw, 1924), 189 pp.; Turgenev, Di ershte libe(First love [original: Pervaia lyubov’]) (Warsaw, 1925), 271 pp.; Turgenev, Klara militsh(Klara Milich) (Warsaw, 1935).  He also compiled in translation a collection of opera arias, Gypsy poems, romances, and songs: Far shtub un estrade (For home and stage) (Warsaw, 1938), 80 pp.  He edited the weekly Hoyz-fraynd (House friend) in Warsaw (1931) and the collection Zumer-tsayt (Summertime) (Warsaw, 1932); co-edited Yidishe shriftn (Lodz, 1948) and Grodner opklangen (Buenos Aires).  Zak’s novellas, novels, and poetry have been translated into Polish, Russian, Hebrew, and German.  His books, Di erd unter blut (The earth under blood), reportage from WWI, and Verbes baym vaser (Willows by the water), poetry, were typeset for publication in 1939 and were lost due to the outbreak of war.  He died in Buenos Aires.

            In 1978 there was published in Buenos Aires: Avrom zak yoyvl-bukh (Jubilee volume for Avrom Zak), 324 pp.