vilify, denounce
詆 centers on attacking someone's reputation with words: vilifying or denouncing them publicly.
詆 combines 言 (speech) with 氐, which likely contributes the sound and may relate to lowering or pushing down, fitting the idea of verbal attack.
Words (言) that push someone down (氐) are used to vilify and denounce them.
For テイ, imagine a critic taking aim with words: they take a verbal shot, and the sound 'tay' (like the start of 'take') cues テイ as they denounce their target.