'vividly-decorated' is a modern English compound formed from the adverb 'vividly' and the past-participle adjective 'decorated'. 'vividly' is from 'vivid' + the adverbial suffix '-ly'; 'vivid' ultimately traces to Latin 'vividus' (from 'vivere', 'to live'), meaning 'lively' or 'bright'. 'decorated' comes from Latin 'decorare' (from 'decor', 'beauty, ornament') via Old French 'decorer' into Middle English.

'vivid' entered English via Old French/Latin influence and developed from Latin 'vividus'. 'decorare' transformed into Old French 'decorer' and then into Middle English (e.g., 'decoraten'/'decoraten') before becoming the modern English 'decorate' and its past-participle 'decorated'. The compound form is a direct modern combination of adverb + past participle.

Individually, 'vivid' originally related to 'life' or 'liveliness' and shifted toward 'bright' or 'intense'; 'decorare' originally meant 'to make seem fitting or comely' and evolved toward 'to embellish or ornament'. Together, the compound's meaning—'brightly or strikingly ornamented'—is a straightforward combination of those senses.