Obsessionally

Part of speech: adverb

Definitions

1. Marked by a pervasive and consuming fixation on particular thoughts or actions that may hinder everyday life
2. Relating to a profound and often irrational focus on specific ideas or tasks, frequently affecting normal behavior
3. Characterized by an intense and overwhelming preoccupation with certain thoughts or behaviors that disrupt daily functioning

Etymology: "Obsessionally" is an adverb built from "obsessional" with the common suffix "-ly", which turns an adjective into an adverb meaning "in the manner of" that adjective. So the word describes doing something in an obsessional way, with intense, persistent fixation. The adjective it rests on, "obsessional", goes back to "obsession", a word rooted in the Latin "obsidere", meaning "to besiege" or "to sit down before" a place. The image is of an enemy surrounding a fortress and refusing to leave, which is a useful picture of a thought that will not let go. Over time the sense moved from an external siege to an internal one, a mind held captive by a single idea.