יָשַׁר (b. h.; cmp. אָשַׁר) to be firm, strong, healthy; to be straight, right. יִישַׁר כֹּחֲךָ or חֵילְךָ ‘may thy strength (health) be firm’, a phrase of approval and thanks. Sabb. 87ᵃ, a. fr. (play on אֲשֶׁר, Ex. XXXIV, 1) י׳ כ׳ ששברת, be thanked for having broken (the tablets). Gen. R. s. 54 (play on וישרנה, I Sam. VI, 12) י׳ חילכם; a. e.—(יֵשַׁר) יִישַׁר (sub. כחך) thanks! right! Ber. 42ᵇ; Sabb. 53ᵃ; Erub. 32ᵇ; a. fr.—Cmp. אַיְשַׁר.
    Pi. - יִישֵּׁר, יִשֵּׁ׳ to straighten, direct, to make firm. Ex. R. s. 1 (ref. to יֵשֶׁר, I Chr. II, 18) זה כלב שיי׳ את עצמו that is Caleb who kept himself straight (did not yield to the rest of the spies). Num. R. s. 8 (ref. to Ps. L, 23 ושם דרך) המְיַישֵּׁר אורחותיו וכ׳ he who directs his ways straight (pays regard to his doings).—Part. pass. מְיוּשָּׁר, f. מְיוּשֶּׁרֶת. Pirké d’R. El. ch. X דרכי מי׳ לפני my way is levelled before me.—Meg. 18ᵇ (ref. to יישרו, Prov. IV, 25) מְיוּשָּׁרִין הן אצל וכ׳ they remain firm with (in the memory of) &c.