违 is a bound form (b.f.) — it never stands alone as an independent word in modern Chinese. Instead, it appears as a morpheme in formal or literary compounds. Its most common meanings are 'to violate' or 'to disobey' (e.g., 违反 'to violate', 违法 'illegal'), and less commonly 'to be separated from' (e.g., 久违 'long time no see'). You'll encounter it in legal, ethical, and social contexts.