Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
rallentando is an adjective and adverb meaning "(music) gradually decreasing in tempo". It carries 2 recorded senses.
slowing down
“this passage should be played rallentando”
music
Definitions, synonyms and semantic relations for rallentando come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.