The answer is:
1. nocturne (a piano composition or a picture of a night scene): night
2. tricycle (a vehicle similar to a bicycle, but with three wheels): three
3. maternity (motherhood, the act of becoming a mother): mother
4. September (originally from the Latin word septem, which was the seventh month of the Roman year): seven
Affixes are morphemes attached to word roots, such as suffixes or prefixes. Root words are the basic forms of words without any affixes. For example, in the word tricycle, the prefix is tri-, and the root word is cycle.