Definition of drop off

The phrase "drop off" in its current usage refers to a decrease or decrease in intensity or quantity. Its origin can be traced back to the nautical and aviation industries in the early 20th century. In nautical terms, "drop off" initially referred to a sudden and marked increase in depth from a relatively shallow area in the ocean floor. This terminology was later adopted by pilots to describe the sudden loss of altitude due to an unexpected fluctuation in air currents. After being transferred to the air, the use of "drop off" evolved to describe a decrease in something else. For example, in meteorology, it's used to explain a significant drop in temperature, air pressure, or precipitation. In other contexts, the phrase has been extended as a colloquialism to describe a drop-off in demand, sales, or productivity, as well as a decrease in quality, such as the "drop-off" in English fluency for non-native speakers. Overall, the derivation of the expression "drop off" demonstrates how technical terms get assimilated into common English, broadening their meanings and expanding their usage as time passes.