overhead has 9 distinct synonyms spread across 5 of its 9 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. Its 2 recorded opposites are surface, subsurface.
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.
the expense of maintaining property (e.g., paying property taxes and utilities and insurance); it does not include depreciation or the cost of financing or income taxes
(computer science) the processing time required by a device prior to the execution of a command
(computer science) the disk space required for information that is not data but is used for location and timing
(nautical) the top surface of an enclosed space on a ship
located or originating from above
“an overhead crossing”
2 of the 9 recorded senses carry no synonym, antonym or related term, so they are not shown above. Every sense, with its definition and examples, is on the full entry for overhead.
Synonyms, antonyms and the broader and narrower relations for overhead come from Princeton University’s WordNet. Full sources and licences.