liveliness; bustle; cheerfulness
The quality of being lively, bustling, or full of activity and cheerful noise. Often used to describe places, events, or atmospheres.
I like the liveliness of festivals.
The bustle of this town continues until night.
賑やかさ describes the lively, bustling feeling of a place or gathering, the opposite of the quiet emptiness of 寂しさ.
Noun form of the na-adjective 賑やか (lively), derived from the kanji 賑 (bustling, prosperous) and the adjectival suffix やか. The exact historical derivation is uncertain, but the word has been used since at least the Edo period.