Definitions of frequent:

• verb:   be a regular or frequent visitor to a certain place
• verb:   do one's shopping at; do business with; be a customer or client of
• adjective:   frequently encountered

  Example: "A frequent (or common) error is using the transitive verb `lay' for the intransitive `lie'"

• adjective:   coming at short intervals or habitually

  Example: "A frequent guest"