לְאַלְתַּר, לְאַלְתָּר, אַלְתָּר

There is a word לְאַלְתַּר in modern Hebrew, meaning "immediately". There is also another word that means the same: מִיָּד, and all its relatives: מִיָּדִיּוּת, תֵּכֶף וּמִיָּד. Anyway, the word לְאַלְתַּר and the verb אַלְתָּר/לְאַלְתַּר (to improvise) sound to close to English word "to alter" (which originates from Latin), so it sounded suspicious to me, and I made some little research on the topic. It sounded like the Hebrew word comes from the meaning "to adjust, to change", with a slight semantic shift towards "to make immediate change."

Apparently, לְאַלְתַּר has nothing to do with "altering". The word "alter" comes from the same Latin root as "alternative", and its general semantics is rather "another of the same kind", "different". The word לְאַלְתַּר though comes from the Aramaic word אַתַּר, with a preposition עַל: "(right) on (the) place": עַל אַתַּר. This evolved (into עַלְתַּר and) into אַלְתַּר - and all this most probably happened in conversational language duric Mishnaic period, because in the new age no Hebrew scholars would allow guttural letters to drop out that easy.