Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
columnar is an adjective meaning "having the form of a column". It carries 2 recorded senses.
having the form of a column
“trees with columniform trunks”
“columnar forms”
“a columnlike tree trunk”
Definitions, synonyms and semantic relations for columnar come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.