i-adjective
stiff; formal; ceremonious; strict
Describes a person, atmosphere, or manner that is overly formal, rigid, or lacking warmth. Often used negatively for situations that feel constrained or uncomfortable.
See also: 堅苦しい
彼の挨拶はかたっ苦しくて、みんな緊張した。
His greeting was so stiff that everyone got tense.
このレストランはかたっ苦しい雰
This restaurant has a formal atmosphere and you can't really relax.
A similar adjective without the geminated っ. It carries the same meaning of stiffness and formality, but かたっ苦しい is more emphatic and colloquial.
Means 'hard' or 'stiff' in a physical sense, but can also describe a person as rigid or formal. かたっ苦しい focuses specifically on an overly formal or constrained social atmosphere.
Derived from 堅苦しい (かたくるしい) with an emphatic geminated っ inserted, giving a more colloquial and intensified feel. The base 堅苦しい combines 堅い (hard, stiff) and 苦しい (painful, difficult).