one-to-one

[ wuhn-tuh-wuhn ]

/ ˈwʌn təˈwʌn /

Also one-one. (of the relationship between two or more groups of things) corresponding element by element.

Origin of one-to-one

First recorded in 1870–75

The very fact of depicting at one-to-one carries special representational weight.

Magic Bus |Blake Gopnik |July 3, 2012 |DAILY BEAST
“The closest I came to discussing this was in February 2009 when I had a one-to-one meeting,” Coltart said.

In Zimbabwe, a Longtime Foe Sees a Different Side of Robert Mugabe |Eli Lake |May 23, 2012 |DAILY BEAST
One-to-one relationships beg for attention as your ruler Pluto is challenged by Venus.

Zodiac Beast: April 24-30 |Starsky + Cox |April 23, 2011 |DAILY BEAST
Here are a few basic suggestions: In baking, sorghum can be used in place of molasses on a one-to-one basis.

Pancakes' New Topper |Stacey Slate |December 8, 2009 |DAILY BEAST

But there is not a one-to-one correspondence between sunspots and S-Regions.

Disturbing Sun |Robert Shirley Richardson
The transformer below this has a one-to-one ratio, and is called the insulating transformer.

Cyclopedia of Telephony and Telegraphy, Vol. 2 |Kempster Miller
So by their one-to-one logic we should either hate back or go away.

Planet of the Damned |Harry Harrison

one-to-one

(of two or more things) corresponding exactly

denoting a relationship or encounter in which someone is involved with only one other person one-to-one tuition

maths characterized by or involving the pairing of each member of one set with only one member of another set, without remainder

a conversation, encounter, or relationship between two people