When I was in 4th grade, my rebbi taught us a Rashi in which he explains a Pasuk by simply saying "Complaint" (קומפליינט or some similar transliteration), meaning the voice in the Pasuk was dissatisfied with something. Where is this?
(Inspired by this question)
You might be thinking of Rashi to Ex. 15:24, where he explains the reflexive form וילונו ("they complained," or more literally, "they were becomplained") by comparing it to French decomplaisant se, where se is similarly reflexive.
(He also uses קומפליינ"ט complaint as the translation of מתנודד in Jer. 31:17, and קומפלויינ"ט comploint (?) for ומרודי in Lam. 3:19.)
Otzar Laazei Rashi on Tanach gives also the following variations (the Latinizations are his):
קונפליינדר"א (conpleindre) - Job 2:11 (not found in standard editions)
קונפליינ"ט (conpleint) - Jer. 1:6, 4:31
קונפליינט"א (conpleinte) - Job 42:11
as well as, in the volume on Gemara, the following:
קומפליינ"ץ (compleinz) - Rosh Hashanah 34a (standard editions have קומפלייני"א)
קונפליינ"ט (conpleint) - Bava Basra 9a
So maybe indeed your teacher showed you the one in Rosh Hashanah?
