1. serving to complete or enhance something; supplying what is lacking
Usage: formal or technical usage
2. relating to or denoting a pair of things that together form a complete whole
Usage: technical, especially in biology and linguistics

Examples

• The two reports provide complemental information that together gives a complete picture.
• In linguistics, complemental clauses complete the meaning of certain verbs.
• The complemental colors in the design work together to create visual balance.
• These complemental skills make the team more effective.
• The study offers complemental evidence to support the hypothesis.