Improper movement
Improper movement is a illicit movement from an A-bar-position to an A-position, as in (i):
(i) * [IP Johni seems [CP t'i [IP ti knows it all]]]
The intermediate trace, t'i, being a variable since it occupies an A-bar position, violates principle C of the Binding Theory, because it is A-bound by John.
Link
Utrecht Lexicon of Linguistics
References
- Chomsky, N. 1986b. Barriers, MIT Press, Cambridge, Mass.
- Haegeman, L. 1991. Introduction to Government and Binding Theory, Oxford, Blackwell.