antiviral agent

NOUN
15 LETTERS · STARTS WITH A

antiviral agent is a valid 15-letter word worth 18 points in Scrabble and 23 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
A1N1T1I1V4I1R1A1L1A1G2E1N1T1
1 + 1 + 1 + 1 + 4 + 1 + 1 + 1 + 1 + 0 + 1 + 2 + 1 + 1 + 1 =18 PTS
DOUBLE WORD → 36TRIPLE WORD → 54
MEANING

What does antiviral agent mean?