adverb
1.
Synonyms: well 3, altogether, completely, entirely, fully, perfectly, ||plumb, quite, utterly, wholly
2.
in a detailed and complete manner
thoroughly investigated the accusations
Synonyms: completely, detailedly, exhaustively, in and out, inside out, up and down
Idioms: item by item, to the last detail
Contrasted words: casually, offhandedly, sketchily, superficially
Antonyms: cursorily
3.
Synonyms: very 1, exceedingly, exceptionally, extremely, highly, hugely, notably, rattling, remarkably, strikingly
4.
Synonyms: hard 3, assiduously, dingdong, earnestly, exhaustively, intensely, intensively, painstakingly, unremittingly