noun

• (figurative) A substance or material on the edge of something, resembling such a strip of fabric.
  "Nothing moved in sky, land, or sea, except a frill of milkwhite foam along the nearer angles of the shore, shreds of which licked the contiguous stones like tongues."
• (photography) A wrinkled edge to a film.
• (figurative) Something extraneous or not essential; something purely for show or effect; a luxury.
  "My name is Sammy Carleton. Not ‘Mr.’ Carleton, but just plain Sammy. I’m a regular no-nonsense man with no fancy frills about me. I want you to call me Sammy."
• (zoology) The relatively extensive margin seen on the back of the heads of reptiles, with either a bony support or a cartilaginous one.
  "A large admiral lizard leapt up on a rail, stood on hind legs with fore legs raised like hands and watched for a moment […], then loped down the cess-path with arms swinging and iridescent frill flying out like a cape […]"

verb

• (transitive) To make into a frill.
• (intransitive) To become wrinkled.
• (transitive) To provide or decorate with a frill or frills; to turn back in crimped plaits.
  "And I will be bold to ſay my two girls have had a pretty good education, and capacity, [...] they underſtand their needle, breadſtitch, croſs and change, and all manner of plain-work; they can pink, point, and frill; [...]"

verb

• (intransitive, obsolete, falconry) To shake or shiver as with cold (with reference to a hawk).
• (intransitive, obsolete, falconry) To cry (with reference to a bird of prey).
  "1688, Randle Holme, The Academy of Armory, Chester: for the author, Book 2, Chapter 13, “Of the Voices of Birds,” p. 310, The Eagle Frilleth, or Scriketh The Hawk, as Falcon, Gawshawk, and all such Birds of Prey, cryeth, peepeth, or frilleth."