痴 is a bound morpheme that appears in many compounds: 痴迷 (chīmí, obsessed), 痴心 (chīxīn, infatuated), 痴呆 (chīdāi, dementia), 花痴 (huāchī, boy/girl crazy). As a suffix, X痴 means 'X fanatic' — 书痴 (book nerd), 情痴 (hopeless romantic).
history
In Buddhism, 痴 (chī) is one of the Three Poisons (三毒: 贪嗔痴 — greed, anger, ignorance). It represents delusion or ignorance that prevents enlightenment.