› to employ someone to do a job: fill a vacancy/post/position It took us over a year to fill that vacancy.
› to do a job: fill a vacancy/post/position A former state district judge will fill the vacancy created following the CEO's resignation. He was political editor of the Sunday Mirror, then filled the same role at Today newspaper.
› to provide something such as a product or service that someone wants or needs: fill a gap/niche The theory is that the government's venture-capital funds can fill a gap in the market for start-ups.fill a demand/need A new business must fill both a need and a demand. Selling something people need but don't want is noble but not profitable.
› to supply a customer with the product or service they have requested: The defence ministry called for bids to fill an order for 126 fighter jets.