Definition
The number that corresponds to a given logarithm. If the logarithm of a number N is L, then N is the antilogarithm of L. In base-10 logarithms, the antilogarithm of L equals 10 raised to the power L.
Plain English
It is the reverse of a logarithm. A logarithm asks, 'What power do I raise the base to in order to get this number?' The antilogarithm gives you that number back when you already know the power.
Context Anchor
Seen in older navigation, engineering, and performance references that use logarithm tables or math formulas.
Derivation
From the Greek 'anti-' meaning 'against' or 'opposite,' combined with 'logarithm.' It literally means the opposite operation of taking a logarithm — going back from the exponent to the original number.
Why Pilots Care
Most pilots will not use antilogarithms in normal cockpit work, but the term can appear in older aviation manuals, engineering references, or calculation methods. Knowing it prevents a math step from becoming a reading barrier.
Analogy
An antilogarithm is like an undo button for a logarithm. The logarithm changes a number into a log value; the antilogarithm changes that log value back into the original kind of number.
Intuition Check
Do not read “anti” as meaning the number is negative or opposed to flying. Here it means the reverse math step: changing a logarithm back into its original number.
Example Sentence 1
If the logarithm of 100 is 2, then the antilogarithm of 2 is 100.
Example Sentence 2
After taking the logarithm during a weight-and-balance step, the pilot found the antilogarithm to return to the usable starting number.