leery (adj.) Look up leery at Dictionary.com
"untrusting, suspicious, alert," 1718, originally slang, with -y (2), and perhaps from dialectal lere "learning, knowledge" (see lore), or from leer (v.) in some now-obscure sense. OED suggests connection with archaic leer (adj.) "empty, useless," a general Germanic word (cognate with German leer, Dutch laar), of unknown origin.