tight-lipped

See also: tightlipped

English

tight +‎ lipped

tight-lipped (comparative more tight-lipped, superlative most tight-lipped)

(literally) Having the lips pressed tightly together, hence, not speaking.
- 1922, Rafael Sabatini, Captain Blood: His Odyssy, chapter XXV:
  He would have sprung upon Captain Blood, who stood aloof, alert, tight-lipped, and watchful.
- 1936, F.J. Thwaites, chapter XV, in The Redemption, Sydney: H. John Edwards, published 1940, page 162:
  Gaining the dak, they were joined on the veranda by four tight-lipped men.
(idiomatic) Unwilling to divulge information.
- 2022 May 4, “Network News: RAIB looking into emergency brake application of train at Peterborough”, in RAIL, number 956, page 12:
  The open access operator has remained tight-lipped over what may have caused the driver to suddenly apply the brake, but stressed that safety was its priority.

unwilling to divulge information