Definify.com
Webster 1913 Edition
Complemental
Comˊple-men′tal
,Adj.
 1. 
Supplying, or tending to supply, a deficiency; fully completing. 
“Complemental ceremony.” Prynne.
 2. 
Complimentary; courteous. 
[Obs.] 
Shak.
 Complemental air 
(Physiol.)
, 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 
(Zool.)
, peculiar small males living parasitically on the ordinary hermaphrodite individuals of certain barnacles.
 Webster 1828 Edition
Complemental
COMPLEMENTAL
,Adj.
  Definition 2025
complemental
complemental
English
Adjective
complemental (not comparable)
- Of the nature of a complement; completing.
- Complementary.
- (obsolete) Additional; supplemental, accessory; ancillary.
- (obsolete) Of the nature of a ceremony that is not essential but accessory; ceremonial; ceremonious; formal.
- (obsolete) Of persons: accomplished; talented; experienced.
-  (obsolete) Complimentary.
- (Can we find and add a quotation of Shakespeare to this entry?)
 -  1603, John Florio, translating Michel de Montaigne, Essayes, London: Edward Blount, OCLC 946730821, I.39:
- I have no skill in ceremonious letters, which have no other substance, but a faire contexture of complemental phrases and curteous words.
 
 
Derived terms
- complemental angle
- complemental air
- complemental male
References
- J[ohn] A. Simpson and E[dward] S. C. Weiner, editors (1989) The Oxford English Dictionary, 2nd edition, Oxford: Clarendon Press, ISBN 978-0-19-861186-8.