a concave shape whose distinguishing characteristic is that the concavity faces downward
"The artist carefully carved a shallow dome into the wooden ceiling to create an intimate, inward-facing curve above the table."
a stadium that has a roof
"The new sports dome opened last week, allowing fans to watch games regardless of the weather outside."
a hemispherical roof
"The ancient cathedral features a massive stone dome that covers its central nave."
A structural element resembling the hollow upper half of a sphere.
"The architect designed a grand hall featuring a massive stone dome over its entrance."
In plain English: A dome is a round, roof-like structure that curves upward from all sides without any flat top.
"The city's famous landmark is topped with a large glass dome that lets sunlight shine into the museum below."
Usage: Use "dome" as a noun to describe any architectural structure with a rounded, hemispherical roof or ceiling. As a verb, it specifically means to cover something in this curved shape rather than using synonyms like cap or crown.
To give a domed shape to.
"The architects decided to dome the entrance of the new library to create a grand, circular ceiling."
A surname.
"Captain Dome led his team to victory in the final game of the season."
Borrowed from Middle French dome, domme (modern French dôme), from Italian duomo, from Latin domus (ecclesiae) (literally "house (of the church)"), a calque of Ancient Greek οἶκος τῆς ἐκκλησίας (oîkos tês ekklēsías). Doublet of domus and duomo.