עִיצּוּם, עִצּ׳ m. (עָצַם) 1) strength. Lam. R. to III, 4 (expl. עצמותי, ib.) [read:] עִיצּוּמִי בָּנַי שהיו כבני העצומים (he broke) my strength, that is, my sons who were like the sons of the mighty. —2) essence, self. Sabb. 86ᵇ; Yalk. Ex. 278 (ref. to זכור את וכ׳, Ex. XIII, 3, a. XX, 8) מה להלן בעִיצּוּמוֹ של יום וכ׳ as there the word was delivered on the selfsame day (of the exodus), so it was here on the selfsame day (on a Sabbath day). Yoma 81ᵃ (ref. to בעצם, Lev. XXIII, 30) על עיצומו של יום וכ׳ labor on the day itself is punished with extinction (contrad. to תוספת). Men. 68ᵇ, a. e. —3) pl. עִיצּוּמִים, עִיצּוּמִין, עִצּ׳ (cmp. אַסְמַכְתָּא) surety, a promise made with the condition of a forfeit in case of failure to fulfill it. Y. B. Bath. X, 17ᶜ bot. ע׳ … גבי R. A. decided a promise of forfeit to be collectible. Y. Gitt. V, 47ᵇ, [read as:] Y. B. Bath. l. c. אע"ג דלית לר׳ יוסי גבי ע׳ … דאינון גביי וכ׳ although R. J. declares ʿitsumim not to be collectible, he admits that they are collectible in the case of those who indenture their sons to a trade, because the livelihood of men requires such a measure.