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if and only if

A term used by mathematicians and logicians to indicate that something happens under very specific conditions. Often seen in proofs and theories.
1) The sum a geometric sequence is given by a/(1-r) if and only if |r| < 1.

2) In a bar:
dumped guy: "My girlfriend left me because I told her I loved her!"
other guy: "What a bitch!"
dumped guy: "No, it's all my fault, she's a mathematician, and I should have said 'I love you and only you'".
by berkanator September 6, 2005
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Recommended if you live in a hot/humid climate, exercise, or have a physically demanding job to manage sweat, oil, and odor, indoor job, live in a cooler climate, or have dry/sensitive skin. Only necessary if you are heavily soiled or sweating profusely
Recommended if you live in a hot/humid climate, exercise, or have a physically demanding job to manage sweat, oil, and odor, indoor job, live in a cooler climate, or have dry/sensitive skin. Only necessary if you are heavily soiled or sweating profusely
by GravelWincher123 February 24, 2026
mugGet the Recommended if you live in a hot/humid climate, exercise, or have a physically demanding job to manage sweat, oil, and odor, indoor job, live in a cooler climate, or have dry/sensitive skin. Only necessary if you are heavily soiled or sweating profusely mug.

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