calentar

To heat or warm up — used constantly for food, weather, engines, and bodies, plus a wide set of idioms (calentar motores, to warm up/prepare; calentarse, to get worked up or angry). One of the most frequent -ar verbs a learner will encounter.

• Calenté la sopa en el microondas. — I heated up the soup in the microwave.
• El equipo salió a calentar antes del partido. — The team went out to warm up before the match.
• Se calentó mucho cuando le llevaron la contraria. — He got really worked up when they contradicted him.

Calentarse (reflexive) commonly means "to get angry/worked up" in everyday speech, not just "to become warm" — a learner who only knows the literal sense may miss this very common figurative use, and should also watch out for vulgar regional uses of calentarse/estar caliente around romantic arousal in some countries.

• expression Calentar motores — A widely used fixed expression from motorsport jargon, where engines are run for a while to reach optimal temperature before a race — used figuratively across the Spanish-speaking world to mean preparing or warming up for any demanding activity or event.