D defs.my
Entry 2 senses Webster, 1913

Complemental

· Com·ple·men·tal · IPA
01 a. Supplying, or tending to supply, a deficiency; fully completing.
  1. 1.
    Supplying, or tending to supply, a deficiency; fully completing.
  2. 2.
    Complimentary; courteous.[Obs.]
Phrases & compounds
Complemental air — the air (averaging 100 cubic inches) which can be drawn into the lungs in addition to the tidal air, by the deepest possible inspiration.
Complemental males — peculiar small males living parasitically on the ordinary hermaphrodite individuals of certain barnacles.