1997 MIT Mystery Hunt Puzzle 19 Solution

Each of the words is made of three trigrams and one additional letter:

• BEL-LY(a)C-HER
• CA(n)T-ALO-UPE
• EVA-NGE-LI(s)T
• FOR-ESH-ADO(w)
• HEL-ICO-PT(e)R
• IMB-(r)OGL-IOS
• (i)NST-RUM-ENT
• MAR-A(s)CH-INO
• MIC-R(o)FI-CHE
• OVE-RDU-(b)BED
• PAR-AM(e)C-IUM
• RE(s)T-AUR-ANT
• SEE-RSU-CK(e)R
• SPO-ONE-RI(s)M
• (t)ETR-AHE-DRA

The extra letters spell ANSWER IS OBESEST so the answer is OBESEST.