valid
adjective
val·id
| \ ˈva-ləd
\
\
Definition of valid
1
: having legal efficacy or force
especially
: executed with the proper legal authority and formalities
a valid contract
2a
: well-grounded or justifiable : being at once relevant and meaningful
a valid theory
b
: logically correct
a valid argument valid inference
3
: appropriate to the end in view : effective
every craft has its own valid methods
4
of a taxon
: conforming to accepted principles of sound biological classification