The expression "Winning streak" is referring to several wins in a row, meaning there are no losses in between. Fx Say that a football team has won 3 matches in a row (one after the other, no losses in between). That would be a winning streak of 3 consecutive matches. If a team wins 2 matches, loses a third and then wins the fourth match, they would have won 3 matches - but it wouldn´t be a winning streak, because the chain of winning outcomes was broken by the loss in the third match.

a series of successes or failures, especially in a sport or in gambling Examples : a streak of good luck to hit (= have) a winning streak to be on a winning / losing streak a lucky / unlucky streak

agree with Steinar. "the cares that hang around me through the week seem to vanish like a gambler's lucky streak, when we're out together dancing cheek to cheek" ♪ Fred Astaire ♥ just another example of the word :D