Facultatively
The Century Dictionary and Cyclopedia
In a facultative manner.
Wiktionary, Creative Commons Attribution/Share-Alike License
adverb.
In a
facultative
manner
Word Usage
"Aren't they ALL folksy, blue-eyed, facultatively bipedal teratomas over there?"
Antonyms
Words with the opposite meaning
mandatorily
Synonym
Words with the same meaning
optionally