cruzar

To cross — a street, border, river, or one's arms/legs/fingers. It's one of the most common verbs for physical movement or positioning across or over something, and the reflexive cruzarse adds the separate sense of running into someone by chance.

• Cruzamos la calle cuando el semáforo se puso en verde. — We crossed the street when the light turned green.
• Cruza los dedos para que todo salga bien. — Cross your fingers so everything goes well.
• Me crucé con mi antiguo profesor en el metro. — I ran into my old teacher on the subway.

Don't confuse plain cruzar (to cross something) with reflexive cruzarse (to run into someone/cross paths) — "crucé a mi vecino" sounds like you physically crossed him, not that you bumped into him; that needs me crucé con mi vecino.

• expression "Cruzar los dedos" — The common gesture and phrase for wishing for good luck or a favorable outcome — crossing the index and middle fingers, the direct Spanish equivalent of English's "fingers crossed."