well-grounded or justifiable; relevant and meaningful
logically sound
having legal efficacy, esp executed according to the proper formalities
a valid contract
(often + for) able to be used lawfully, esp for a stated period or under certain conditions; legally acceptable
This ticket is valid for three months
validity /vəʹliditi/ noun
validly adv
validness noun
[early French valide from Latin validus strong, from valēre to be strong]