Trött is used when it's just one person, trötta is used when there are more than one. Most adjectives in swedish use an a in the end to show that it's more than one subject involved.
Ohh I didnt know there are specific terms for each gender.. Great! Thanks!
Well, there aren't really, except for this little one. It's in use but not very important. The ending -a works for everyone anyways.
I keep confusing trött with the Dutch trots... too bad most sentences will still make sense then
Same here with Croatian 'trut' meaning 'worker ant'. Makes sense because worker ants are more tired than the others :D