Though the word “smidgen” is often used to describe anything that is very small, in formal use, a smidgen is equal to one-32nd of a teaspoon. Likewise, two smidgens are about equal to a pinch. The word “smidgen” is thought to originate from an old Irish or Scots Gaelic word, smidean, which means a very small bit.
More about measurements:
The amount in a pinch has actually changed over time. Though today it’s about equal to a 16th of a teaspoon, older cookbooks call a pinch about an eighth of a teaspoon. Generally speaking, a pinch is just however much of an ingredient the cook can pinch between his or her fingers.
There seems to be a lot of confusion about what constitutes a drop. Measurements of a drop range from one-60th of a teaspoon to one-120th of a teaspoon. Measuring generously, it would take 7.5 drops to make a tad, or an eighth of a teaspoon.
Other commonly used measurement words that actually have an exact equivalent include a tick, which is 0.01 seconds; and a shake, which is 10 nanoseconds. There also is the humorously used beard-second, which is equal to 5 nanometers.