A nonsense word invented in the late 1950s for a language acquisition experiment into the learning of morphology. The drawing of a mythical animal (a wug) was presented to children, and the child was told: ‘This is a wug’. Then the experimenter would point to a second picture, saying ‘Now, there’s another one. There are two of them. There are two ___’. If the children had learned the plural ending, they would say wugs; if they had not, they would say wug. Using several such nonsense words in a range of morphological contexts, much basic information was obtained concerning the order and timing of the acquisition of grammatical morphemes.
本世纪50年代为研究儿童如何学会研究形态变化的语言习得实验而发明的一个无意义词。画一只神话中的动物（一只“蛙狗”）给儿童看并告诉他：This is a wug“这是一只蛙狗”。然后实验者指向另一张画片，说：“看，这儿又是一只。一共两只。”There are two “有两只 ”。如果儿童已学会加复数词尾，就会接着说wugs；如果还未学会，就会说wug。在一系列形态上下文中用几个这样的无意义词测试，就可获知语素习得的词序和时间阶段。