rule of thumb

Etymology
Attested since 1658. Of uncertain origin, but probably based on the use of the thumb as reference for various measurements. For instance, one theory notes that the inch originated as the distance between the base of the thumbnail and the first joint, another notes the practice of approximating the general direction of the wind by wetting the thumb then raising it in the air. A third theory notes that English royal banquet plate setters used the distance of their thumbs to equally space each plate from the table edge.

The erroneous claim that the term referred to the maximum thickness of a stick with which it was permissible for a man to beat his wife has appeared in The Washington Post and Time; it may originate from Del Martin's 1976 book Battered Wives.

Noun

 * 1) A general guideline, rather than a strict rule; an approximate measure or means of reckoning based on experience or common knowledge.
 * 2)  Approximated, guesstimated.
 * 1)  Approximated, guesstimated.
 * 1)  Approximated, guesstimated.
 * 1)  Approximated, guesstimated.

Synonyms

 * See also Thesaurus:saying

Translations

 * Arabic: قَاعِدَة عَامَّة
 * Catalan: regla general
 * Chinese:
 * Mandarin: 拇指規則, , 經驗法則, 一般規則
 * Danish: tommelfingerregel
 * Dutch:
 * Finnish:, peukalosääntö
 * French: règle générale, ,
 * German: ,
 * Greek: πρακτικός κανόνας, βασικός κανόνας
 * Hungarian:
 * Icelandic: þumalputtaregla
 * Italian: a lume di naso
 * Japanese: 大体の目安, 目の子算
 * Macedonian: општо начело
 * Norwegian:
 * Bokmål: tommelfingerregel
 * Nynorsk: tommelfingerregel
 * Portuguese:, ,
 * Russian: практи́ческое пра́вило, эмпири́ческий приём
 * Spanish: regla general
 * Swedish:
 * Turkish: pratik kural