对(duì) - correct, right; toward; pair in Mandarin

对 (duì) functions in multiple grammatical roles: as an adjective meaning "correct" or "right," as a preposition meaning "toward" or "regarding" (对我来说, as for me), and in compounds meaning "a pair" (一对, a couple/pair). As an interjection it confirms what someone has said, equivalent to "right," "correct," or "exactly."

The traditional form 对 shows a hand on the left and a "mound/ancient measure" on the right, originally depicting alignment or matching. This sense of "matching, being correct" remains central. The preposition use - 对你说 (to say to you), 对他好 (to be good to him) - is extremely productive and one of the key grammar patterns learners need to master early.