Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
taetrĭcus (tētr-), a, um, adj. [taeter], forbidding, harsh, crabbed, gloomy, sour, stern, severe (perh. not ante-Aug.; cf.: tristis, severus): puella, Ov. A. A. 1, 721: Sabinae, id. Am. 3, 8, 61: taetricus et asper censor udorum, Mart. 12, 70, 4: lector, id. 11, 2, 7: deae, i. e. the Fates, id. 4, 73, 6; 7, 96, 4: taetrica ac tristis disciplina Sabinorum, Liv. 1, 18, 4: animus (ccupled with horridus), Sen. Ep. 36, 3: febres, Mart. 6, 70, 8: tubae, fierce, warlike, id. 7, 80, 2.