Add spaces: Ablackjackisthereforeanaceandany10-pointcard,withtheadditionalrequirementthatthesebeyourfirsttwocards.Ifyousplitapairofaces,forexample,andthendrawaten-pointcardononeoftheaces,thiswillnotcountasblackjack,butratheratotalof21.
A blackjack is therefore an ace and any 10-point card, with the additional requirement that these be your first two cards. If you split a pair of aces, for example, and then draw a ten-point card on one of the aces, this will not count as blackjack, but rather a total of 21.