'dialogue-heavy' is a compound formed in English from 'dialogue' and the adjectival element '-heavy'. 'dialogue' originates from Greek, specifically the word 'dialogos', where 'dia-' meant 'through' or 'between' and 'logos' meant 'speech' or 'reason'. '-heavy' originates from Old English 'hefig', meaning 'having great weight'.

'dialogue' came into English via Latin and Old French ( Medieval Latin/French forms) from Greek 'dialogos' and became Middle English 'dialogue' (or variants) before reaching modern English. The element '-heavy' developed from Old English 'hefig' into Middle English 'heavy' and was extended in Modern English to form compounds meaning 'having a large amount of' (e.g., 'emotion-heavy'). The compound 'dialogue-heavy' is a modern English formation combining these elements.

Initially, 'dialogue' meant 'conversation' (a meaning that has largely remained consistent). 'Heavy' originally meant 'weighing a lot', but over time it developed a secondary sense of 'having a large amount of (something)', which allows formations like 'dialogue-heavy' meaning 'containing a lot of dialogue'.