Morpheme: Minimal Meaningful Language Unit

A morpheme is the smallest meaningful unit found in a language. It can represent a piece of semantic content (like 're-' in 'redo') or serve a grammatical function (like the past tense '-ed' in 'walked').

The question requires identifying this minimal unit based on its capacity for meaning or function. Analyzing the options:

• Meaningful: This aligns perfectly with the definition of a morpheme as the smallest unit carrying semantic or grammatical significance.
• Arbitrary: While words can be arbitrary symbols, 'arbitrary' doesn't capture the essential *meaningful* aspect required for a morpheme.
• Phonological: This relates to sounds (phonemes), which are smaller than morphemes and usually don't carry meaning on their own.
• Orthographic: This concerns spelling and writing systems, not the core functional units of language meaning.

Therefore, the defining characteristic of the minimal unit of language, whether for semantic content or grammatical function, is that it is meaningful.