Meaning: the Christmas child, (or, if you're feeling literal, the little boy of The birth) a shortened version of which - El Niño - is the nickname for a warm current off Peru which begins around Christmas time. This has given its name in turn to the larger, related climate pattern of El Niño/La Niña.
Usefulness: 1 (Could be used in all sorts of overblown metaphors about the arrival of Christmas and / or the Christ child, or as a slightly-more-interesting-than-usual way to start a conversation about the weather.)
Logofascination: 2 (Mainly in terms of the linguistic history - the Latin nativitas became Navidad, was shipped around the world to Peru, adopted to describe some weather, shortened, and then hijacked by scientists. If you keep following the trail you get to Japanese, via the El Niño "Modoki".)
Usefulness: 1 (Could be used in all sorts of overblown metaphors about the arrival of Christmas and / or the Christ child, or as a slightly-more-interesting-than-usual way to start a conversation about the weather.)
Logofascination: 2 (Mainly in terms of the linguistic history - the Latin nativitas became Navidad, was shipped around the world to Peru, adopted to describe some weather, shortened, and then hijacked by scientists. If you keep following the trail you get to Japanese, via the El Niño "Modoki".)