Bi and Heterosexual

Bi noun - A heavy brittle diamagnetic trivalent metallic element (resembles arsenic and antimony chemically); usually recovered as a by-product from ores of other metals.

Heterosexual is an antonym for bi in having relations with either gender topic.

Heterosexual adjective - Sexually attracted exclusively to members of the opposite sex.

Bi is an antonym for heterosexual.