obsess

verb

Etymology: 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.

1. To be preoccupied with a single topic or emotion.

   “Some people are obsessed with sports.”

   “The [Isaac] Newton that emerges from the [unpublished] manuscripts is far from the popular image of a rational practitioner of cold and pure reason. The architect of modern science was himself not very modern. He was obsessed with alchemy.”

2. To dominate the thoughts of someone.

   “Thoughts of her obsess my every waking moment.”

3. To think or talk obsessively about.

   “Stop obsessing over it, will you!”