עִיכּוּב, (עָכַב) keeping back, hinderance, prevention. Tem. 32ᵃ sq. אין בה אלא ע׳ גיזברין בלבד there is nothing to prevent the offering of the sacrifice, except that we must await the appearance of the Temple treasurers (as representatives of the owners).—Esp. hinderance, a circumstance which makes a religious act invalid, indispensable condition, absolute necessity. Y. Pes. VII, 34ᵇ top (ref. to כי אם צלי אש, Ex. XII, 9) שינה עליו הכתוב לע׳ the text has an extraordinary (emphatic) expression about it to intimate that the roasting of the Passover sacrifice over fire is indispensable. Ib. II, 29ᵇ bot. לע׳ תאמרת the rule that the unleavened bread to be eaten on the Passover night must not contain any fruit juice has been laid down as an indispensable condition, opp. למצוה, v. מִצְוָה; a. e.