What term describes someone who is prone to excessive tearfulness and mourning?

The term that describes someone who is prone to excessive tearfulness and mourning is "lachrymose." This word is derived from the Latin "lacrima," meaning "tear." It specifically refers to individuals who are tearful or mournful often, highlighting a tendency to respond emotionally with sadness or grief.

In the context of the choices provided, "inimitable" refers to something that cannot be imitated, typically used to describe a unique style or quality. "Lassitude" indicates a state of physical or mental weariness, not related to emotional responses to sadness. "Libertine" describes a person who is morally unrestrained or someone who indulges in sensual pleasures without regard for morals, which is unrelated to the emotional state suggested by the question. Thus, "lachrymose" is the term that precisely captures the essence of excessive sorrowfulness and tearfulness.