Similar words
hervidor
Worth distinguishing: hervidor is a kettle; caldera is a boiler, bigger and often industrial.
Similar in other languages
French
chaudière
chaudière is the French word for the same thing — both mean "boiler."
Portuguese
caldeira
caldeira is the Portuguese word for the same thing — both mean "boiler."
Practice
1 What does caldera mean?
boiler
2 Fill the gap: La ___ está rota.
Full sentence: La caldera está rota. (The boiler is broken.)
3 Which fingerprint chart matches caldera?
caldera: neutral register, common frequency, general domain, neutral connotation.