complement v. compliment

The word complement deals with parts completing a whole. It can be:

• Something that completes a construction. In grammar, a complement is a phrase that completes a predicate.
• The number of items required to make a complete set, as in the phrase ‘a full complement’.
• Either of 2 counterparts that complete each other, such as complementary angles, which add to 90°, or musical complements, which are 2 intervals that span an octave.
• Something added to make perfect; ‘Sriracha sauce is an ideal complement to pizza’.

A compliment is an expression of praise or congratulation.

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