tournament
1)比赛;锦标赛;联赛
Our team won the championship in the basketball tournament. 我们队在篮球联赛中赢得冠军。
competition
1)竞争,角逐
Competition among youths to enter the best colleges is intense.年轻人想进一流大学的竞争是很激烈的。
2)比赛,竞赛;赛会
I entered a chess competition and finished third.我参加了象棋比赛名列第三。
English speaking composition 英语演讲比赛
contest
1) 争夺,竞争
A bitter contest developed between the two men for that position.那两个人为得到这一职位展开了激烈的竞争。
2).竞赛,比赛
He took part in the composition contest and won a prize. 他参加作文比赛并得了奖。
race
1) 速度比赛
What about the sailboat race? 帆船竞赛怎么样？
They doped the horse up and it won the race. 他们给那匹马服用兴奋剂，它赢了比赛。
总而言之，tournament和race侧重于体育比赛，但race还有比喻义，如arms race军备竞赛。competition和contest侧重于体育之外的比赛。
