C18: perhaps from obsolete sense (to look askance) of leer
leery for learners of EnglishPowered by COBUILD (lɪəri)
1. graded adjective & adjective [usu v-link ADJ]
If you are leeryof something, you are cautious and suspicious about it and try to avoid it. [informal] [+ of] ⇒ Executives say they are leery of the proposed system. [+ about] ⇒ They were leery about investing in a company controlled by a single individual.
If someone looks or smiles at you in a leery way, they look or smile at you in an unpleasant way, usually because they are sexually interested in you. [disapproval] ⇒ ...a leery grin.
All I could hear was Jean-Luc Marnier's name and see his leery face.Robert Wilson A DARKENING STAIN`You should, though as a general rule burglars are leery about gainingentry from the front of a building -- too exposed.Forbes, Bryan A SONG AT TWILIGHTThey'd keep on feeling leery , moreover, until they got the official word on what Jasper Flodge had died of.MacLeod, Charlotte SOMETHING IN THE WATERFeeling in need of his support, though still leery of his motives, she had given in finally.Wilcox, James SORT OF RICH