Theory advanced especially by American philosophers Saul Kripke (1940- ) and Hilary Putnam (1926- ) that whether a currently used name names a certain object depends on whether current use of the name causally depends on its use by people who originally dubbed the object with that name.
'Homer' names whatever person the Greeks used it (or a Greek variant of it) to address (even if that person was not a poet at all). 'Homer' does not mean (as the rival descriptive theory of names holds) 'who ever wrote the Iliad and Odyssey'.
Kripke and Putnam also extend the theory to cover words for 'natural kinds', like 'tiger' or 'water'. 'Water' names whatever stuff it was first applied to, and does not mean 'H2O' or 'colorless tasteless liquid', and so on.
Also see: CAUSAL THEORIES OF REFERENCE
S P Schwartz, ed., Naming, Necessity and Natural Kinds (1977)