Null affixation is a process by which new words are formed by adding an affix which happens to be phonologically null. Many linguists (e.g. Bloomfield (1933), Kiparsky (1982)) account for conversion by assuming that a null affix is added to a base.
they account for verbs such as to clean, to thin, to slow, to warm etc. by assuming that these have the structure [[...]A 0]V.
- Bloomfield 1933. Language, Holt, New York.
- Kiparsky, P. 1982. From Cyclic Phonology to Lexical Phonology, in: Hulst, H. van der and N. Smith (eds.) The Structure of Phonological Representations (I), pp.131-175