Na-adjective (keiyodoshi), Adverb taking the 'to' particle, Noun
busy; hurried; rushed
Expressions (phrases, clauses, etc.)
yours sincerely; yours in haste
letters ending with this start with 前略, 冠省, etc.see 草々
Na-adjective (keiyodoshi), Noun
simple; brief; quick
Archaic
Also written 怱々【そうそう】、匆匆【そうそう】、怱怱【そうそう】