thumb nut

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wing nut

wing nut
A nut having projections so that it can be tightened with one finger and the thumb.
References in periodicals archive ?
Using your fingers, tighten the thumb nut by turning it clockwise to lock it into position.
The Thumb Nut series of thumbscrews with internal female thread can be used as a stand-alone thumbscrew or in conjunction with the company's Instant Thumbscrew Knob to create a thumbscrew with a check nut, thereby facilitating locking down an adjustment.
Most garden cultivators of this era have two bolts that must be unscrewed in order for adjustments to be made, but the Standards all have the easy-to-use thumb nut, which no doubt contributed to their popularity 100 years ago.