Legal, lawful (5)
I believe the answer is:
licit
I believe this is a double definition.
'legal' is the first definition.
(similar in meaning)
'lawful' is the second definition.
(synonyms)
(Other definitions for licit that I've seen before include "Acceptable" , "Lawful, permitted" , "Permitted by law" , "not banned" , "Within the law" .)