pleat (v.) Look up pleat at Dictionary.com
1560s, used as the verb version of plait (n.) and probably representing an alternative pronunciation. Related: Pleated; pleating.
pleat (n.) Look up pleat at Dictionary.com
"a fold," 1580s, variant of plait (n.). With a gap in the printed record 17c.-18c., but probably it was in continuous oral use.