1) Ancient Greek architecture 
The hypotrachelium is the upper part or groove in the shaft of a Doric column, beneath the trachelium. The Greek form is hypotrakhelion. In classical architecture, it is the space between the annulet of the echinus and the upper bed of the shafts, including, according to C. R. Cockerell, the three grooves or sinkings found in some of the older exa...
• (n.) Same as Gorgerin.
Hy`po·tra·che'li·um noun [ Latin , from Greek ...; ... under + ... neck.] (Architecture) Same as Gorgerin . 
(on a classical column) any member, as a necking, between the capital and the shaft. Cf. trachelium.