For many years, the label on Vivarin listed an ingredient called
Stimucil. (it is no longer included in the formula) What was Stimucil
the buzz word for? Thanks

Hello.

Stimucin was Vivarin's buzz word for caffeine.

From the United States Patent & Trademark Office:
"Mark (words only): STIMUCIN ...
OWNER(S) 1. Beecham Inc....
Caffeine Sold Only as an Integral Component and Active Ingredient in
Stimulant Tablets"
Source:  USPTO Trademark Application and Registration Retrieval system
http://tarr.uspto.gov/servlet/tarr?regser=serial&entry=73419858

Also see the following usenet messages:

"My favorite is Vivarin containing Stimucin(SM)....  Their registered
name for caffeine..."
Cached by Google Groups:
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&client=googlet&selm=CD9G5M.GC8%40sugar.NeoSoft.COM&prev=/groups%3Fq%3Dstimucin%26hl%3Den%26lr%3D%26ie%3DUTF-8%26client%3Dgooglet%26selm%3DCD9G5M.GC8%2540sugar.NeoSoft.COM%26rnum%3D1

"'Stimucin' is SmithKline Beecham's registered trade name for 
caffeine. Caffeine is the only active ingredient in Vivarin."
Cached by Google Groups:
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&client=googlet&selm=7227nb%24hg9%40ash.computing.csbsju.edu

search strategy: 
google groups, vivarin, ingredient, caffeine
trademark database, stimucin

I hope this helps.

The answer was on point.