Palabrota vs. grosería vs. taco
Spanish language has different words to refer to 'swear words', they specifically are 'palabrota', 'grosería' and 'taco'. Although these three words have similar meanings, they are used in slightly different contexts.
Palabrota
A 'palabrota' is a strong or rude swearing word that is usually considered inappropriate or vulgar.
Los niños no deberían decir palabrotas.
(Children should not say swear words.)
Mi abuela se sorprendió cuando escuchó la palabrota que salió de mi boca.
(My grandmother was surprised when she heard the swear word come out of my mouth.)
Grosería
'Grosería' primarily refers to a rude or disrespectful action, gesture or word. It is also used in reference to vulgar or obscene language, but can also refer to poor behavior in general.
No me refería a gritar en el restaurante, eso es una grosería.
(I did not mean shouting in the restaurant, that is rude.)
Las groserías que dijo en presencia de los niños fueron inapropiadas.
(The obscenities he said in the presence of children were inappropriate.)
Taco
'Taco' as a slang can also mean vulgarity or swear word. It is most often heard in Spain, although it might not be understood by some Spanish speakers from Latin America.
El conductor se enojó y soltó un par de tacos.
(The driver got angry and let out a couple of swear words.)
"¡Joder!" es un taco muy común en España.
('Joder!' is a common swear word in Spain.)
Summary
'Palabrota', 'grosería', and 'taco' all refer broadly to obscenities or vulgarity in the Spanish language, although with slightly different connotations. A 'palabrota' is more related to vulgar language, while 'grosería' can reference both impolite actions and words. The term 'taco', generally used specifically in Spain as a slang term for obscenity, might be less known as such among Latin American Spanish speakers.