1. achieve or realize something, carry out a duty
fulfill a dream/engagement/obligation
Both 'fulfil' and 'fulfill' are different spellings of the same word. To 'fulfil' something means to carry it our or to achieve it. If you 'fulfil' a dream, for example, you realise the dream and make it come true. You can 'fulfil an obligation' by carrying out something you have agreed to do. This verb is used more in formal speech than in social situations.