(Appeared in the December 2007 issue of Community News)
Something is inflammable if it tends to ignite at commonly encountered temperatures. Other English words that come from the same Latin root are inflammation, inflame, and inflammatory. At one time, trucks hauling materials that could catch fire easily had signs on them saying INFLAMMABLE. However, too many people apparently thought that flammable means "easily set on fire" and that those the loads on those truck were not easily set on fire. So now such trucks have signs saying FLAMMABLE. That's not really a word in English, but presumably, because of those signs, it soon will be, and inflammable will disappear.
(Will be in the January 2008 issue of Community News)
An action is feckless if it is ineffective or worthless. An incompetent person could also be called feckless. It’s an old word in some Scottish and English dialects, and it comes from the word feck, which is a variant of the English word effect. So something is feckless if it has no effect. Those dialects also had the word feckful, which is the opposite of feckless, but feckful never caught on in mainstream English.
I'm collecting all of these at: http://www.dvorkin.com/davidsdefs.html