תָּסַס (onomatop.) [to hiss,] 1) to bubble, boil, ferment. Ab. Zar. 30ᵇ יין תּוֹסֵס וכ׳ wine in its first stage of fermentation does not come under the law concerning liquids left uncovered (גִּילּוּי); Y. Ter. VIII, 45ᵈ sq.; Tosef. Ter. VII, 15. Ib. וכמה תוסס וכ׳ and how long is it in that inceptive stage? &c., v. preced. Y. Taan. IV, 69ᵃ bot. ראה … תוסס he saw the blood (of the prophet) boil; Lam. R. introd. (R. Josh. 2); (Snh. 96ᵇ; Gitt. 57ᵇ מרתח); a. fr.— to spurt. Cant. R. to III, 6 נתן אצבע על הצור התחילה תוֹסֶסֶת אש he put his finger on the rock, and it began to spurt fire; Gen. R. s. 77 (corr. acc.); Yalk. ib. 132 התחילה האש תוססת (corr. acc.). —3) to cause spurting or sparkling. Tosef. Sabb. VI (VII), 10 התוסס אוד בכותל וכ׳ (not אור; ed. Zuckerm. האומר חתום אוד, corr. acc.) if one strikes a brand against the wall, and says, ‘here it is’, he is guilty of a superstitious practice (v. אֱמוֹרִי), but if he does it for the sake of the sparks, it is permissible.