Final answer:
The small speech units that carry meaning in a language are called morphemes. Phonemes are the basic sound units, whereas semantics and syntax are parts of grammar involved with meaning and sentence structure.
Step-by-step explanation:
The small speech units that carry meaning in a language are called morphemes. Phonemes, on the other hand, are the basic sound units that do not carry meaning by themselves but are used to form morphemes. For example, the word "cats" has two morphemes: "cat" and the plural suffix "-s". Semantics refers to the study of meaning in language, and it is how we understand the meaning of morphemes and words. Syntax is the set of rules that governs the structure of sentences. Both semantics and syntax are parts of a language's grammar and are essential for constructing meaningful sentences and conveying messages effectively.