1. As a noun, meaning a measuring instrument:
It's pronounced "gayj", with a short "a" sound like the "a" in "cat".
2. As a verb, meaning to measure or estimate:
It's pronounced the same as the noun, "gayj".
Example sentences:
* Noun: "The mechanic used a pressure gauge to check the tire pressure."
* Verb: "The police officer gauged the driver's speed."
So, in most cases, the word "gauge" is pronounced with a short "a" sound, similar to the word "cage".