たちまち

Etymology
From. First cited to the  of 759.

Apparently a shift from, the of compound verb , probably from the idea of being. In older texts, this was always followed by the adverbial particle for all senses.

Adverb

 * 1)  at once, in no time at all, in a moment, in a twinkling, immediately, suddenly, all at once, right away
 * 2)  unexpectedly, suddenly, abruptly
 * 3)   actually, really, truly, genuinely
 * 1)  unexpectedly, suddenly, abruptly
 * 2)   actually, really, truly, genuinely