undoubtedlya linking word meaning 'without doubt; certainly'Climate change is undoubtedly one of the most pressing challenges facing humanity today.NoteClimate change is undoubtedly one of the most pressing challenges facing humanity today.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