The word is a modern English compound formed from two distinct Germanic roots. "Thrill" originates from an Old English verb meaning "to pierce," a sensation metaphorically extended to describe a sharp, penetrating feeling of excitement. "Seeking" comes from the Old English verb for "to look for or pursue." The compound "thrill-seeking" logically combines these elements: it describes the active pursuit (seeking) of those piercing moments of intense sensation (thrill). This construction follows a transparent pattern in English where a noun object is combined with a present participle to create a descriptive adjective, clearly conveying the concept of someone who pursues exciting, often risky, experiences.

Structure: thrill (to excite) + seek (to search for) + ing (adjective suffix) - thrill: From Middle English thrillen (to pierce, penetrate), from Old English þyrlian (to pierce), related to þyrel (hole). In this compound, it functions as a noun meaning a sudden wave of intense excitement or emotion. - seek: From Old English sēcan (to go, look for, pursue), from Proto-Germanic sōkijaną. It functions as a verb root meaning to try to find or obtain. - ing: A suffix of Germanic origin forming present participles and adjectives from verbs, indicating the action or quality associated with the verb.