olemus
(a) raamiga, paigutusega vms esiletõstuga tekstiplokk
(b) kasutajaliidese element teksti sisestuseks

Wiktionary:
1. a block of printed text contained within borders that is intended to be read separately from the major text of the page
2. (computing, graphical user interface) a rectangular widget that accepts textual input on an interactive electronic display

ülevaateid
https://en.wikipedia.org/wiki/Text_box