rule of thumb

American  

noun

1. a general or approximate principle, procedure, or rule based on experience or practice, as opposed to a specific, scientific calculation or estimate.

2. a rough, practical method of procedure.

---

rule of thumb British  

noun

1. 1. a rough and practical approach, based on experience, rather than a scientific or precise one based on theory

   2. ( as modifier )

      a rule-of-thumb decision

---

rule of thumb Cultural  

1. A practical principle that comes from the wisdom of experience and is usually but not always valid: “When playing baseball, a good rule of thumb is to put your best hitter fourth in the batting order.”

---

rule of thumb Idioms  

1. A rough and useful principle or method, based on experience rather than precisely accurate measures. For example, His work with the youth group is largely by rule of thumb. This expression alludes to making rough estimates of measurements by using one's thumb. [Second half of 1600s]

---

Etymology

Origin of rule of thumb

First recorded in 1685–95

Example Sentences

A good rule of thumb is that you should have at least six months’ worth of expenses saved up.

From MarketWatch

A good rule of thumb when it comes to friendship, or any relationship really, is that you should never be talking yourself into one.

From MarketWatch

“They need to have a plan, and more than a rule of thumb and arbitrary goals, to live out their retirement.”

From MarketWatch

“The rule of thumb is, if you put your hand up in the direction that the light is coming and you see a shadow, that is enough light for the plant to sense,” she said.

From Los Angeles Times

But it is a reminder that just like AI, traditional rules of thumb for investing aren’t infallible.

From Barron's

Related Words

• criterion