Nowadays, we use this word to mean old and infirm, weak from old age. This usage dates from the mid-19th century. Originally, the word just meant having to do with old age. It comes from a Latin word meaning old. Other words that derive from the same Latin root are senior, senescent (growing old, characteristic of being old), and the Spanish title señor. The medieval English word seneschal, a senior servant, comes from the same root combined with a Germanic word, skalk, for servant. I haven't been able to find out if skalk has any connection to our word skulk, which can mean to evade work. Presumably, one of the duties of the seneschal was to make sure that the lower-level servants didn't skulk.
(Will be published in the September 2010 issue of Denver's Community News.)
The Scrabble word score of senile is 6.
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