Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
high-and-mighty is an adjective meaning "offensively self-assured or given to exercising usually unwarranted power". It carries one recorded sense.
offensively self-assured or given to exercising usually unwarranted power
“an autocratic person”
“autocratic behavior”
“a bossy way of ordering others around”
“a rather aggressive and dominating character”
“managed the employees in an aloof magisterial way”
“a swaggering peremptory manner”
Definitions, synonyms and semantic relations for high-and-mighty come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.