securely has 1 distinct synonym spread across 1 of its 4 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 insecurely.
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.
in a confident and unselfconscious manner
“he acts very securely in front of the camera”
in a manner free from fear or risk
“the outcome of expansion in the sixties and seventies will be an academic hierarchy securely supported by scholastic selection”
1 of the 4 recorded senses carries no synonym, antonym or related term, so it is not shown above. Every sense, with its definition and examples, is on the full entry for securely.
Synonyms, antonyms and the broader and narrower relations for securely come from Princeton University’s WordNet. Full sources and licences.