whatsit

 Longman Dictionary of Contemporary English 5++朗文当代英语 5++LDOCE 5++朗文 5++whats·it /ˈwɒtsɪt $ ˈwɑːts-, ˈwʌts-/ noun [countable]  spokenTHINGNAME OF A THING a word you use when you cannot think of the word you want 那个什么玩意儿〔指想不起名称的东西〕 Try and undo the screw to get the whatsit off. 试着拧开螺丝，把那个小玩意儿拆下来。

Examples from the Corpus

whatsit• Sick of Neighbours It's my neighbour Deardrie - he's a right old interfering whatsit.• The curtains were green with little whatsits along the edge.• Something decidedly peculiar about the boy with the whatsit round his head.• Just enough to work up a sweat, keep the blood moving, tone the old cardio-vascular whatsit.Origin whatsit (1800-1900) what's it?

whats·it nounChineseSyllable  

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whatsit
whats‧it /ˈwɒtsɪt $ ˈwɑːts-, ˈwʌts-/ noun [countable]spoken a word you use when you cannot think of the word you want:
    Try and undo the screw to get the whatsit off.

whats·itBrE /ˈwɒtsɪt/ 🔊NAmE /ˈwɑːtsɪt/ 🔊, /ˈwʌtsɪt/ 🔊 noun (informal, especially BrE) used when you cannot think of the word or name you want, or do not want to use a particular word （想不起名称或不想指明时说）什么来着，某某玩意儿◆I've got to make a whatsit for the party. That's it—a flan. 我得给聚会制作一个什么东西来着。想起来了，一个果馅饼。🔊🔊