"Against the clock" is a common English-language expression or idiom that is generally used when someone feels that he or she doesn't have enough time to complete a task by a deadline, and are, in effect, rushing against the clock to complete it. It is an expression that is often used in business environments where high-volume, high-stress conditions exist. Likely locations where racing against the clock to complete a task would be routine would include newspapers where stories must be completed on deadlines, and stock market trading floors where trades are affected by volatility and the closing bell end to a day's trading. Sports environments are another key area where literally racing against the clock to score often occurs when a team is behind in points with only minutes or seconds left in the game.
The origin of a saying such as "against the clock" is often unclear. This particular clock idiom is one among many related to clocks, and appears to have originated as a shortening of the phrase “race against the clock,” which developed in the mid 1900s in the world of sports. It was used most often to refer to running athletes, such as in marathons and track-and-field events, where performance is timed down to the level of fractions of a second. Other clock-related idioms that are popular and refer to rapidly approaching deadlines include performing tasks at the last minute, last second, or last hour. Completing a task at the "11th hour" or "just under the wire" are also idioms related to rapidly approaching deadlines.
The English language has many idioms related to time. Since the meaning of the words making up an idiom can vary based on the culture in which it is used, it is often necessary to get an interpretation of what it means. Assumptions based on suspected meaning can sometimes result in a mistranslation or wrong understanding. Common time-related idioms in the English language that could easily be misunderstood include such phrases as "better late than never," "a day late and a dollar short," and "at the drop of a hat." Most English idioms can be traced back in western society a century or more, and often have different modern meanings today than they originally did when they first appeared.
Over 3,500 idioms are regularly incorporated into contemporary English spoken language, and often make it difficult for people learning English as a second language to understand the meaning being conveyed. The purpose of some idioms, such as "against the clock," can be guessed with relative ease, but others are nearly impossible to understand the meaning without experience in the specific culture where the language is spoken. There may even be variances to the meaning within the same country or culture. Idioms that can cause non-native English speakers to scratch their heads in bewilderment include examples such as "milk run," "cog in the machine," and "I'll be a monkey's uncle." Native English speakers often forget the meaning of such phrases as well, even though they may use them as they talk without realizing it.