Jastrow: נִימּוּק

נִימּוּק, נִמּ׳ m. (contr. of נעמוק; עָמַק) depth, penetration. Ab. d’R. N. ch. XVIII; Gitt. 67ᵃ ר׳ יוסי נִימּוּקוֹ עמו gave to R. Jose the surname, ‘His depth is with him’, i.e. he has deep reasons for whatever he says. Ib. אלמלא ראיתו נ׳ עמו if thou hadst seen him, (thou wouldst have seen) his depth was &c. Erub. 51ᵃ. Bekh. 37ᵃ מהו דתימא נ׳ עמו you might have thought, we must adopt R. Jose’s opinion because he is known to have deep reasons.