The phrase “full speed ahead” is an idiomatic expression. Rather than meaning that someone is going with great velocity, it means that one is going with enthusiasm, vigor or energy into whatever task it is that is being undertaken. It is the opposite of approaching a goal or task with hesitation, sluggishness, boredom or apathy.
People who are highly driven and motivated to succeed could be said to move “full speed ahead.” A woman who works at a large business and undertakes many projects at work, puts herself fully into all of them and desires to earn a promotion could be said to be going “full speed ahead.” If a man puts everything he has into organizing a charity fundraising event that will benefit the underprivileged and disadvantaged, going all out in terms of advertising, outreach and resources, this phrase would apply to him as well.
The opposite of this phrase can be illustrated by words such as "apathetic," "lackadaisical" or "easygoing." A student who does not study for tests, refuses to take notes in class and does not participate in classroom activities could not be said to be moving “full speed ahead” academically. A basketball player who does not try to catch passes from team members, prevent members of the opposing team from making shots or passes or make shots to help win the game is definitely not playing in a manner that can be described as “full speed ahead.”
This phrase originated in the United States. It is derived from the phrase "full steam ahead," which referred at first to steam engines. In a boat powered by a steam engine, when the boiler reached maximum pressure, it could be said to be moving “full steam ahead.” Like many idiomatic expressions, "full speed ahead" and "full steam ahead" have changed in meaning over the years so that they now refer figuratively to moving quickly instead of literally to an abundance of steam and forward motion in a steam-engine vessel.
Idioms are one type of figurative language, which also includes similes, metaphors, hyperbole and other related literary devices. Figurative language refers to language that might say one thing literally but have another, figurative, meaning. While “full speed ahead,” for example, might appear at first glance to be related to one’s speed or velocity in traveling, it really is a figure of speech referring to the energy or motivation that one puts into a task. Like this expression, many figures of speech require some thought to analyze or to figure out.