0 a practical and approximate way of doing or measuring something: --
A good rule of thumb is that a portion of rice is two handfuls.
1 a method of judging a situation or condition that is not exact but is based on experience: --
As a rule of thumb, the ice on the lake should be at least two inches thick to support one person.
NYA ORD
European
May 10, 2021
DAGENS ORD
Shimmer
rule of thumb