der·i·va·tion 
(dĕr′ə-vāshən)
(dĕr′ə-vāshən)n.
1.
a. The act or process of deriving.
b. The state or fact of being derived; origination: a custom of recent derivation.
c. Something derived; a derivative.
2. The form or source from which something is derived; an origin.
3. Linguistics
a. The historical origin and development of a word; an etymology.
b. The process by which words are formed from existing words or bases by adding affixes, as singer from sing or undo from do, by changing the shape of the word or base, as song from sing, or by adding an affix and changing the pronunciation of the word or base, as Electricity from electric.
c. In generative linguistics, the generation of a linguistic structure through an ordered or partially ordered series of operations on other structures, such as the creation of a surface structure from a deep structure, or of a complex word from its morphological components.
d. The formal description of the process of such generation.
4. Logic & Mathematics A logical or mathematical process indicating through a sequence of statements that a result such as a theorem or a formula necessarily follows from the initial assumptions.
der′i·vation·al adj.