1. Phonological derivation
Kuiper and Allan Chapter 5.6

2. Derivation
The processes which are involved in realising an underlying phonological representation phonetically create a derivation.

3. Example of a derivation
Underlying Representation /kÅngres/
Aspiration kHÅngres
Nasalization kHÅ‚ngres
Vowel Lengthening kHÅ‚˘ngres
Nasal assimilation kHÅ‚˘Ngres
Surface Representation [kHÅ‚˘Ngres]

4. What is a phoneme? It is not a sound.
It is a phonologically distinctive sound.
What makes it distinctive?
Its having a specific set of distinctive features, e.g voicing.
So a phoneme is a bundle of distinctive features.