the word 'worrier' is a transparent english formation built upon the verb 'worry'. the verb itself has a fascinating journey, originating from the old english 'wyrgan', meaning 'to strangle' or 'to kill by compression of the throat'. this literal sense of physical harassment evolved metaphorically in middle english to describe the act of harassing or attacking someone, and later, by the 19th century, to the internal, mental state of being anxious or troubled. the agent suffix '-er' is then appended, following a common english pattern, to denote a person habitually engaged in the action, thus creating a word for someone who mentally 'harasses' themselves with anxious thoughts.

Structure: worri + er worri (from the english verb 'worry', of old english origin, meaning 'to strangle' or 'to harass') + er (agent noun suffix, from old english '-ere', indicating a person who performs an action).