tittaka : [adj.] bitter. (nt.), bitter taste.

A.P. Buddhadatta Mahathera, Concise Pali-English and English-Pali Dictionary [available as digital version from Metta Net, Sri Lanka]

Tittaka (adj.) [cp. Sk. tiktaka from tij] sharp, bitter (of taste) M i.80 (˚alābu), 315 (id.); PvA 47 (id.; so read for tintaka lābu) Dhs 629=Nd2 540 (tittika; enumdbetween lavaṇa & kaṭuka); DhsA 320.

Pali-English Dictionary, TW Rhys Davids, William Stede,