"to look obliquely" (now usually implying "with a lustful or malicious intent"), 1530, from M.E. noun
ler "cheek," from O.E.
hleor "the cheek, the face," from P.Gmc.
*khleuzas "near the ear," from
*kleuso- "ear," from PIE root
*kleu- "to hear" (see
listen). The notion is probably of "looking askance" (cf. figurative development of
cheek). The noun is first attested 1598.
[leer] 
