(idiomatic) To overstep a boundary, rule, or limit; to go too far or do something unacceptable. / To finish a race. / To achieve completion of something. / To cross the equator, as a vessel at sea.

(nautical) A ceremony performed on board ship when members of the crew or passengers cross the equator for the first time.

present participle of cross the line

simple past tense and past participle of cross the line

Third-person singular simple present indicative form of cross the line