na-adjective
Describes a manner or attitude that is short, unfriendly, and lacking warmth. Often used for speech or behavior that feels dismissive or cold.
彼のつっけんどんな返事に傷ついた。
I was hurt by his curt reply.
店員の態度がつっけんどんで、感じが悪かった。
The clerk's attitude was brusque and unpleasant.
Both describe blunt, unfriendly manner. ぶっきらぼう often implies a rough, unrefined bluntness, while つっけんどん emphasizes coldness and a lack of warmth in speech or attitude.
そっけない means cold, indifferent, or unfriendly, but can be used for a wider range of situations. つっけんどん is specifically about blunt, curt speech or behavior.
The origin is uncertain. The kanji 慳貪 (kendon) means 'greedy' or 'stingy', but the connection to the meaning 'blunt' is unclear. The word is thought to be a sound-symbolic formation with the prefix つっ (tsu') adding emphasis.