Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
shoulder-to-shoulder is an adverb meaning "side by side and close together". It carries one recorded sense.
side by side and close together
“the troops marched shoulder-to-shoulder”
Definitions, synonyms and semantic relations for shoulder-to-shoulder come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.