The term 'not as well' can be expressed in two five-letter words: 'WORSE' and 'iller'. The word 'WORSE' is an adverb meaning 'to a greater degree of badness or inferiority'. It is often used to compare two things, such as 'This one is WORSE than that one'. The word 'iller' is an adjective meaning 'of poorer quality or lower standard'. It is also used to compare two things, such as 'This one is iller than that one'. Both words are used to express the idea of something being not as good as something else.