na-adjective
persistent; tenacious; relentless
Describes a person or action that is stubbornly persistent, often with a negative nuance of being annoyingly insistent or not giving up.
彼は執拗に同じ質問を繰り返した。
He persistently repeated the same question.
執拗な追跡で、ついに犯人を捕
Through tenacious pursuit, they finally caught the criminal.
Simplified spelling using よう for the second character; less common but acceptable.
しつこい is a more colloquial and common adjective for 'persistent' or 'insistent', often with a stronger negative nuance of being annoying. 執拗 is more formal and literary.
頑固 means 'stubborn' in a general sense, often referring to a fixed personality trait. 執拗 focuses more on persistent, unyielding behavior in a specific situation.
The kanji 執 means 'to hold' or 'to persist', and 拗 means 'to twist' or 'to be obstinate'. Together they convey the idea of stubbornly clinging to something. The reading しつよう is the standard on'yomi; しつおう is an older, now rare reading.