Semantic shift refers to the process by which the meaning of a word changes over time. This can occur for various reasons, such as cultural changes, technological advancements, or shifts in social attitudes. For example, the word gay originally meant "happy" but has evolved to primarily refer to sexual orientation. Another example of semantic shift is the word literally, which once meant "in a literal manner" but is now often used for emphasis in figurative contexts. Such changes illustrate how language is dynamic and reflects the evolving nature of human communication and understanding.