complémentaire

/kɔ̃.plə.mɑ̃.tɛʁ/
1.
adjective

complementary; completing or enhancing something else

supplementary; additional

Sa compétence est complémentaire à la mienne.

Her skill complements mine.

2.
nounfeminine

supplementary health insurance (short for complémentaire santé, often used in everyday speech)

Ma boîte prend en charge ma complémentaire.

My company covers my supplementary health insurance.