Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
custom-built is a noun and adjective meaning "an item made to the customer's specifications". It carries 2 recorded senses.
an item made to the customer's specifications
built for a particular individual
Definitions, synonyms and semantic relations for custom-built come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.