tightness has 15 distinct synonyms spread across 5 of its 5 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 one recorded opposite is looseness.
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 state occasioned by scarcity of money and a shortage of credit
a tight feeling in some part of the body
“he felt a constriction in her chest”
the spatial property of being crowded together
extreme stinginess
Synonyms, antonyms and the broader and narrower relations for tightness come from Princeton University’s WordNet. Full sources and licences.