formidableanother word for 'big' meaning inspiring fear or respect through being impressively largeThe country faces formidable challenges in modernising its ageing infrastructure.NoteThe country faces formidable challenges in modernising its ageing infrastructure.Elon.io is an online learning platformWe have an entire course teaching IELTS Vocabulary — Band 7+ grammar and vocabulary.Start learning IELTS Vocabulary — Band 7+ now