Some common synonyms of valid are cogent, convincing, sound, and telling. While all these words mean "having such force as to compel serious attention and usually acceptance," valid implies being supported by objective truth or generally accepted authority.

// a valid reason for being absent

// a valid marriage

While the synonyms sound and valid are close in meaning, sound implies a basis of flawless reasoning or of solid grounds.

// a sound proposal for reviving the economy

The words telling and valid are synonyms, but do differ in nuance. Specifically, telling stresses an immediate and crucial effect striking at the heart of a matter.

// a telling example of bureaucratic waste