leer (n.) Look up leer at Dictionary.com
"a significant glance, amorous or malign or both," 1590s, from leer (v.).
leer (v.) Look up leer at Dictionary.com
1520s, "to look obliquely" (since 18c. usually implying a lustful, wolfish, malicious intent), probably from Middle English noun ler "cheek," from Old English hleor "the cheek, the face," from Proto-Germanic *hleuza- "near the ear," from *hleuso- "ear," from PIE root *kleu- "to hear." If so, the notion is probably of "looking askance" (compare the figurative development of cheek). Related: Leered; leering.