Final Answer:
Deictic expression is the linguistic term for a word whose meaning is semantically fixed but can only be understood through context.
Step-by-step explanation:
Deictic expressions are linguistic elements whose interpretation relies on the surrounding context, such as the speaker's location, the listener's perspective, or the temporal setting. The example provided illustrates this concept, where the word "I" takes on different referents (either "Laura" or "Tom") based on the speaker's identity. Deictic expressions are inherently context-dependent and lack a fixed meaning in isolation.
These expressions play a crucial role in communication as they facilitate the speaker's ability to convey specific meanings that are contingent on the immediate context. Deictic elements include pronouns (like "I" or "you") and demonstratives (such as "this" or "that"), and their interpretation requires an understanding of the speaker's spatial, temporal, and social context.