Which term refers to an attitude that is hostile or unfriendly?

The term that refers to an attitude that is hostile or unfriendly is "inimical." This word originates from the Latin "inimicus," meaning “enemy,” and is often used in contexts that describe something that is harmful or adverse. Inimical can describe relationships, environments, or sentiments that are antagonistic, conveying a sense of opposition or unfriendliness.

In contrast, the other choices do not capture the essence of hostility. "Ineluctable" means inevitable or unavoidable, referring to outcomes that cannot be escaped. "Lachrymose" describes someone who is tearful or prone to crying, associated with sadness rather than hostility. "Inimitable" refers to something that is so unique it cannot be imitated, focusing on singularity rather than any unfriendly disposition. Thus, "inimical" stands out as the appropriate term for describing a hostile or unfriendly attitude.