panel has 10 distinct synonyms spread across 6 of its 10 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a group of people gathered for a special purpose as to plan or discuss an issue or judge a contest etc
a piece of cloth that is generally triangular or tapering; used in making garments or umbrellas or sails
(computer science) a small temporary window in a graphical user interface that appears in order to request information from the user; after the information has been provided the user dismisses the box with `okay' or `cancel'
electrical device consisting of a flat insulated surface that contains switches and dials and meters for controlling other electrical devices
“he checked the instrument panel”
decorate with panels
“panel the walls with wood”
Synonyms, antonyms and the broader and narrower relations for panel come from Princeton University’s WordNet. Full sources and licences.