Strange, or unusual
Antonyms of familiar could be new, abnormal, or not original
familiar
known, familiar
Unfamiliar Strange Alien Uknown
usual, familiar, common, regular
the most likely antonyms for strange is familiar, usual or expected.
Something that is unknown is unfamiliar, uncertain, undecided or pretty much not known. Antonyms are certain, decided, identified, known, or familiar.
The words gigantic and minute are antonyms. (The word minute is a most familiar as a unit of time equal to 60 seconds, however, it is also a word meaning very small - and when it is used for that meaning, it is also pronounced differently, rhymes with cute.)
Some antonyms (words with opposite meanings) to fantastic are: Plain, ordinary, standard, normal, mediocre, expected, indifferent, realistic, real, average, acceptable, familiar.
Antonyms
antonyms
The antonym of unknown is known. When you know something then you won't not know that thing that you know. Unknown means to not know something.