Definitions of legal:

• adjective:   established by or founded upon law or official or accepted rules
• adjective:   having legal efficacy or force
• adjective:   of or relating to jurisprudence

  Example: "Legal loophole"

• adjective:   relating to or characteristic of the profession of law

  Example: "The legal profession"

• adjective:   allowed by official rules

  Example: "A legal pass receiver"