The results of a study of chain compounds, heavily modified noun phrase structures, used in the language of three engineering journals are presented. The findings conlude that: chain compounds appear to be more common in American than British English; chain compounds can be classified in several groups according to their structure, the most common being the noun group (e.g., lap-and-shoulder strap) and the preposition/adverb + noun group (e.g., through-the-lens viewfinder). No systematic rules of metamorphosis are apparent for compound formation, but the tendency is toward simpler forms with minimal closed-system items. Their word class status seems to be somewhere between nominal and adjectival, and when used with other premodifiers, they usually appear closest to the head. They can be characterized roughly as either concrete or figurative expressions. These forms are generally self-explanatory, and may serve to disambiguate and condense information. In contrast to chain compounds used in other fields, such as advertising, engineering chain compounds appear to serve a special communicative purpose of clarifying and differentiating where a shorter term could be ambiguous. (MSE)