Which term describes a group of words with a meaning not deducible from the individual words?

The term that describes a group of words with a meaning not deducible from the individual words is "idiom." Idioms are expressions that have a figurative meaning which differs from the literal meanings of the individual words. For example, the phrase "kick the bucket" is an idiom that means to die, and its meaning cannot be understood by analyzing the words "kick" and "bucket" separately.

Phrases are simply groups of words that work together but do not necessarily have a meaning that can't be inferred from the individual words. Alliteration refers to the repetition of the same initial consonant sounds in a sequence of words, which does not relate to meaning. A simile is a figure of speech that directly compares two different things, often using the words "like" or "as," which describes relationships rather than offering a non-literal meaning. Therefore, "idiom" is the appropriate term to define expressions where the meaning cannot be derived from its constituent words.