The phrase "a valid definition" is correct and usable in written English.
You can use it when discussing whether a particular definition is acceptable or meets certain criteria.
Example: "The term 'democracy' has a valid definition that encompasses the principles of equality and representation."
Alternatives: "an acceptable definition" or "a legitimate definition".
We develop a valid definition of technological radicalness which states that a successful radical invention is: (1) novel; (2) unique; and (3) has an impact on future technology.
Multilevel structural equation modeling revealed that dispositional teacher enthusiasm positively predicted students' interest, which was fully mediated by students' perceived enthusiasm, providing the basis of a valid definition of teacher enthusiasm.
After the success of Men in Black 3 – although that's a relative term, based on whether or not you believe "slightly better than Men in Black 2" to be a valid definition of success – the site would have you believe that Will Smith is only interested in making sequels from now on.
On its own, a lower cost isn't a valid definition of efficiency: efficiency would entail achieving an equivalent benefit for that lower cost.
The goal hence is not to provide a valid definition of domestication but rather to examine the representations related to it.
Taber (2005, 16), on the other hand, suggests that it is possible to construe MS 1.1.4 as a valid definition, and indeed such a construal was proposed by an earlier commentator, the so-called Vṛttikāra quoted at length by Śābara in his Śābarabhāṣyam.
I don't want my kids and future generations thinking that term is acceptable or has any valid definition going forward in the 21st century.
We propose that a more valid definition of recovery should define a change point until which the syndrome is relatively continuous, but after which a return of the syndrome will become reasonably unlikely.
14 Although recently a new definition of remission was proposed, a fully valid definition of remission for RA is still not available, even though the most stringent ones seem to be better in terms of predicting long-term outcomes.
A very valid definition of biography is that it is "a fiction conceived within the bounds of the observable facts".
The term "e-commerce" still lacks a universally valid definition, but even if you just bundle B2B and B2C transactions under it, it's a multi-trillion dollar business globally.
