fertiliser UK /ˈfɜːtəlaɪzə/US /ˈfɜːɹtəlaɪzəɹ/ noun3 •A natural substance that is used to make the ground more suitable for growing plants.The farmer spread fertiliser across the fields.Organic fertilisers are usually better for the environment. •A chemical compound created to have the same effect. •(offensive) Human remains, especially obscured or to be forgotten. formsfertilisers