From Longman Dictionary of Contemporary Englishwelliewel‧lie /ˈweli/ noun British English 1 [countable] informalDCC a wellington2 [uncountable] spoken informal physical effort or force that you use to move or hit something You need to give it some wellie.
Examples from the Corpus
wellie• It's like walking a tightrope in size-15 wellies.• And putting the boot in ... the recycling service for wellies.• So Flora put on her green wellies and Jane her black ones, and they marched out over the hills.• Remember that stepping into wellies is always easier than trying to pull them on.• Perhaps the countryside has much to offer that is not just wellies, point-to-points and mulch.• It's got 100 watts of wellie.• The seeds sprouted and the fuchsia cuttings struck, and now the little red wellies look wonderful. 