English

line noun definition in Tennis topic from the Oxford Advanced Learner's Dictionary

line

 noun: Tennis topic
[countable] a long thin mark on the ground to show the limit or border of something, especially of a playing area in some sports The ball went over the line. Be careful not to cross the line (= the broken line painted down the middle of the road). Your feet must be behind the line when you serve (= in tennis). They were all waiting on the starting line.