This article is from the Puzzles FAQ, by Chris Cole email@example.com and Matthew Daly firstname.lastname@example.org with numerous contributions by others.
What exceptional words contain other words?
longest non-trivial charade IN-DISC-RIM-IN-A-TI-ON (16)
longest forward and reverse charade
longest snowball or rhopalic T-EM-PER-AMEN-TALLY (15)
longest reverse rhopalic HETERO-TRANS-PLAN-TAT-IO-N (21)
highest ratio of subwords/length (logogram)
FIRESTONE: RE, TO, ON, NO, IF, FIR, IRE, RES, TON, ONE, NOT, RIF, FIRE,
IRES, REST, TONE, FIRES, STONE, SERIF (20/9)
longest charlinkade FORESTALL: FOREST, ALL; FORE, REST, TALL (9)
longest alternade TRIENNIALLY: TINILY, RENAL (11)
shortest three-letter-minimum word deletions
PILGRIMAGE: RIM, GAG, PILE; GRIM, LAG, PIE
Unless noted otherwise, all words occur in Webster's Third New International
Dictionary, Merriam-Webster, Springfield, MA, 1961.