When against is an element in a phrasal verb, eg go against, run up against, look up the verb.
preposición
1(in opposition to)[+person]contra;en contra de;[+plan]en contra de
what have you got against me?¿qué tiene usted en contra de mí?;¿qué tiene usted contra mí?;I spoke against the planhablé en contra del proyecto;I see nothing against itno veo nada en contra;he was against itestaba en contra;se opuso a ello;he was against goingestaba en contra de ir;it's against the lawla ley lo prohíbe;es ilegal;it's against the rulesno lo permiten las reglas;conditions are against uslas condiciones nos son desfavorables;luck was against himla suerte le era contraria
his lack of experience is against himto swim against the current
to stand or run against sb(Pol)presentarse en contra de algn
to be up against itestar en un aprieto
now we're really up against it!¡ahora sí tenemos problemas!
he hit his head against the wallse dio con la cabeza contra la pared;he leant the ladder against the wallapoyó la escalera contra la pared
to lean against a table
3(in front of)contra
against the lightcontra la luz;a contrasol;the hills stood out against the sunsetlas colinas se destacaban sobre la puesta del sol
4(in comparisons)
(as) againstcontra;en contraste con;six today, as against seven yesterdayseis hoy, en comparación con siete ayer
5(for)
refund available against this voucherse devuelve el precio al presentar este comprobante;everything was ready against his arrivaltodo estaba listo para su llegada
adverbio
en contra
well, I'm againstbueno, yo estoy en contra;there were 20 votes againsthubo 20 votos en contra
