na-adjective
spasmodic; erratic; fitful; sporadic
Describes actions, events, or behaviors that occur suddenly and irregularly, often without warning or pattern. Commonly used with verbs like 起こる, する, なる.
彼の発作的な行動に周りは戸惑った。
People around him were puzzled by his erratic behavior.
この地域では発作的な停電がよく起
Sporadic power outages often occur in this area.
断続的 means intermittent with on-and-off repetition, whereas 発作的 implies more unpredictable, seizure-like irregularity.
Compound of 発作 (ほっさ, 'spasm, fit, attack') + 的 (てき, '-like, -ic'). The word 発作 is itself composed of 発 (はつ, 'depart, emit') and 作 (さ, 'make, occur').