text box

noun2

1. •
   A block of printed text contained within borders that is intended to be read separately from the major text of the page.

   • The graphic design of secondary schoolbooks, which includes many text boxes, captions, labelled diagrams, thought bubbles, etc., introduced a certain level of noise into the scanning and OCR[.] — 2018
2. •
   A rectangular widget that accepts textual input on an interactive electronic display.