D defs.my
Entry 1 sense Webster, 1913

Plano-concave

· Pla·no-con·cave · IPA
01 a. Plane or flat on one side, and concave on the other; as, a plano-concave lens. See Lens.
  1. 1.
    Plane or flat on one side, and concave on the other; as, a plano-concave lens. See Lens. See: Lens