peep
v.
1
"glance" (especially through a small opening), mid-15c., perhaps alteration of Middle English piken (see peek, v.). Peeping Tom "a curious prying fellow" [Grose] is from 1796 (see Godiva).
2
"make a short chirp," c.1400, probably altered from pipen (mid-13c.), ultimately imitative (compare Latin pipare, French pepier, German piepen, Lithuanian pypti, Czech pipati, Greek pipos).
n.
1
1520s, first in sense found in peep of day, from peep, v.1; meaning "a furtive glance" is first recorded 1730.
2
"short chirp," early 15c., from peep, v.2; meaning "slightest sound or utterance" (usually in a negative context) is attested from 1903. Meaning "young chicken" is from 1680s. The marshmallow peeps confection are said to date from 1950s.