/therr"teen"/ , n.
1. a cardinal number, 10 plus 3.
2. a symbol for this number, as 13 or XIII.
3. a set of this many persons or things.
adj.
4. amounting to 13 in number.
[ bef. 900; late ME thirttene, var. of ME thrittene, OE threotene; c. D dertien, G dreizehn, ON threttan. See THREE, -TEEN ]