Obsessive means given by nature to dwelling on a single idea. An obsessive personality, obsessive about detail, obsessive checking.
It names a lasting trait rather than the temporary state of being caught up in something. In psychiatry it is precise: obsessive-compulsive disorder involves unwanted thoughts and the rituals done to relieve them, and it is a serious and treatable illness.
1adjectiveobsessiveGiven by nature to dwelling on a single idea to an unhealthy degree.
“She's obsessive about her diet and weighs every piece of food she eats.”
obsessive is a quality.
Proto-Indo-European
*sed-
Latin
obsessus
English
obsess
English, today
obsessive
Built from
From obsess + -ive. obsess comes from Latin obsessus, perfect passive participle of obsideō (“sit on or in, remain, besiege”), from ob- (“before”) + sedeō (“to sit”); see sit, session, etc.; compare assess, possess.
Etymology from Wiktionary, CC BY-SA