adjective Date: 1820 1. of or relating to the grant of permission, authority, or privilege , optional , of or relating to a mental faculty, 3. taking place under some conditions but not under others , exhibiting an indicated lifestyle under some environmental conditions but not under others , ~ly adverb
FACULTATIVE
Meaning of FACULTATIVE in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012