for
This charity is what I want to fight for for a long time.
The sentence uses 'for' first as part of the phrasal verb 'fight for' and then as a preposition indicating duration.
Meanings (pronounced /fɔːr/)
indicating the purpose, recipient, or beneficiary of an action
- This gift is for you.
- She fought for justice all her life.
indicating the length of time over which something extends
- I've lived here for twenty years.
- Wait for a moment.
Word origin
From Old English for ('before, in front of, because of'), one of the most ancient prepositions in English, from Proto-Germanic *fur, from Proto-Indo-European *per- ('forward, through'). The same root underlies 'fore', 'before', 'forward', and Latin per ('through').
Fun fact
'For' is one of the most overloaded function words in English, with at least a dozen distinct uses (purpose, recipient, duration, exchange, cause, support, distance, etc.). Many languages use different prepositions for these senses; English makes 'for' shoulder all of them.