This article is from the alt.usage.english FAQ, by Mark Israel misrael@scripps.edu with numerous contributions by others.
On its AOL message board, Merriam-Webster Editorial Department
writes: "The notion that the sports term 'love' comes from the
French "l'oeuf" seems to be another popular fallacy; so far, our
etymologists have been unable to find any evidence that "oeuf" was
ever used in a 'zero' or 'goose-egg' sense in reference to game
scores. A more probable, if less imaginative, explanation can be
found in the Oxford English Dictionary, which links this sense of
'love' to the phrase 'for love' (i.e. 'without stakes, for
nothing')."
 
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