Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
thwartwise is an adjective meaning "extending or lying across; in a crosswise direction; at right angles to the long axis". It carries one recorded sense.
extending or lying across; in a crosswise direction; at right angles to the long axis
“cross members should be all steel”
“from the transverse hall the stairway ascends gracefully”
“transversal vibrations”
“transverse colon”
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for thwartwise come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.