The term "agostic interactions" is typically used in the context of inorganic and organometallic ligand systems. The term refers to an interaction between a metal center and usually a C-H bond and is typically indicated in diagrams with a dotted line or arrow from the H atom to the metal center. The M-H distance is usually close and the C-H (or other) bond is stretched somewhat.

Geoff Hutchison
Northwestern Chemistry