Stopper comes from the verb 'stop' (Old English 'stoppian', to plug or close up, ultimately from Vulgar Latin '*stuppare', to stop with tow) plus the agentive suffix '-er'. The historical chain includes Old English stoppian and Latin *stuppare. The quoted older senses, "stop", "stoppian", "*stuppare", and "-er", supply the semantic anchors for stopper. The formation is best read as suffixal and borrowed: the word stopper carries its older form-history into a compact English lexical shape. In present English it is used as a noun, "a plug for sealing a bottle or other container". Related English forms include stop and stopple. The result is a noun whose etymology preserves both the older form and the later English specialization.