A "stalker" is a person who obsessively follows or harasses someone, often in a repetitive and unwanted manner. This behavior can cause fear, anxiety, or distress to the individual being stalked. Stalking can occur in various forms, such as physically following someone, sending unwanted messages, or spying on them, and it is considered a serious crime in many jurisdictions.
The word "stalker" comes from the verb "stalk," which means to pursue stealthily. The verb "stalk" originated from the Old English "stalcian," meaning to walk or move stealthily, often in hunting contexts. The noun "stalker" emerged in English in the 15th century.