gauge

There are two gages: one refers to pledges or securities and is no longer in common general use, and the other is a variant spelling of gauge, which in the noun form refers broadly to measurement (“fine-gauge wire”) or a standard by which something is measured (“polls are a good gauge of how voters might vote”). The earliest evidence we have for the noun gauge goes back to the 15th century, when English spelling was not yet standardized, and the word in question was spelled gauge and gage with roughly equal frequency. Gauge began to be preferred in the late 19th century for most general uses. Some claim that gage appears as a variant more frequently in the U.S., though our evidence shows that the vast majority of uses for gage are from specialized and technical industries, such as mechanical engineering, manufacturing, and electronics, and that these uses of gage are global, not limited to the U.S. Nonetheless, total use of the word gage is small when compared to the total use of the word gauge.

The verb gauge, which refers to measuring or estimating, also has a variant gage. This variant appears to show up primarily in informal sources, though not often. Gauge is by far the preferred spelling in general usage for both the noun and the verb; we encourage you use it.