فَاعٍ

Angry and foaming [with anger]. (IAar, M, K.)

And [the feminine] فَاعِيَةٌ A woman (TA) wont to calumniate; synonym نَمَّامَةٌ. (K, TA: in the CK الثُّمامَةُ is put for النَّمَّامَةُ.)