Simply put, a lexical verb is a verb that shows action, one that can be “looked up” in a lexicon (or a dictionary). It is a term used when discussing compound verbs—it is the verb that names the action itself, minus all auxiliaries: jump is a lexical verb; will jump, can jump. did jump, are verbs with auxiliaries (will, can, did), plus the root or lexical verb “jump”. When parsing or diagramming sentences, the term comes in handy, but don’t let the term get in the way of your actual expression. Common lexical verbs are give, know, do, live, etc. “Lexical” is simply an adjective (meaning “word list”) to show the main verb before auxiliaries are added to show tenses, etc. Good writers choose expressive lexical verbs rather than use a lot of adverbs: "trudge" vs. "walk slowly", for example.