sandhi contraction: so + amhi
Analysis. so (now, at this moment) + amhi (I am, present tense of atthi). A colloquial contraction joining a temporal adverb with the copula, common in narrative and dialogue.
Etymology. amhi descends from PIE *h₁es- (to be), which yields English is, Latin esse, Sanskrit asmi. The root appears bare in the present tense without thematic vowel, a mark of archaism. so (now, this) is demonstrative, akin to Sanskrit sa- and related to the root of Latin sic (thus, so).
Meanings from the Digital Pāḷi Dictionary; morphology and etymology by Claude.
Lite mode — plain HTML for e-readers and old browsers. Full version