Many compound nouns are formed by the third person singular of the present tense of an infinitive, followed by the plural (or, occasionally, singular) form of the noun that would be the object of the verb.
For example, take the verb parar, “to stop.” What stops a fall is a parachute, thus para + caídas (“falls”) = paracaídas (“parachute”). What stops water is an umbrella, thus para + aguas = paraguas (“umbrella”). (These nouns, in spite of ending in –s, remain grammatically singular and masculine.) A sampling of such nouns, the meaning of which can often be deduced and some of which you have already seen, follows:
|el limpiaparabrisas||windshield wiper|
|el pararrayo(s)||lightning rod|
|el salvavidas||life jacket, life guard, life boat|
|el tocadisco||record player|
|el trabalenguas||tongue twister|
Although the above combination is common, other compound nouns are also possible, such as the following: