Gwirfoddol, a. voluntary
Gwirfoddoldeb, n. voluntariness
Gwiriad, n. a verifying
Gwiriadwy, a. verifiable
Gwiriant, n. a verification
Gwiriedigaeth, n. verification
Gwiriedigaethu, v. to verify
Gwirin, a. of pure or true nature
Gwirineb, n. verity, truth
Gwirio, v. to verify, to assert