Longman Dictionary of Contemporary English
Wiktionary
a. 1 Matching each member of one set with exactly one member of another set. 2 (context chiefly UK English) Involving direct communication between two people. (non-gloss definition: Used especially to refer to situations in which one person is teaching one other person.) 3 (context mathematics of a function English) injective, being an injection: having the property that no two elements of the domain are mapped to the same image. n. A personal relationship between two people.
WordNet
adj. used of relations such that each member of one set is associated with one member of a second set
Wikipedia
One-to-one or one to one may refer to:
In systems analysis, a one-to-one relationship is a type of cardinality that refers to the relationship between two entities (see also entity–relationship model) A and B in which one element of A may only be linked to one element of B, and vice versa. For instance, think of A as countries, and B as capital cities. A country has only one capital city, and a capital city is the capital of only one country
In a relational database, a one-to-one relationship exists when one row in a table may be linked with only one row in another table and vice versa. It is important to note that a one-to-one relationship is not a property of the data, but rather of the relationship itself. A list of mothers and their children may happen to describe mothers with only one child, in which case one row of the mothers table will refer to only one row of the children table and vice versa, but the relationship itself is not one-to-one, because mothers may have more than one child, thus forming a one-to-many relationship.
Usage examples of "one-to-one".
Because the local government had hired the Frisians at a monthly flat rate, cost cutting had a direct, one-to-one effect on President Hammer's profit margin.
What Hesper views here is not the sky itself, nor even any one-to-one equivalent of it, but simply the nospace correlative of the sky, a map of energy sources in realspace as they have been translated into utterly alien nospace terms.
It involved a Mercator projection of the planet Earth-a common, rectangular, classroom wall map-but with the equator drawn to one-to-one scale.
It involved a Mercator projection of the planet Earth -- a common, rectangular, classroom wall map -- but with the equator drawn to one-to-one scale.
The Map of Mars stood forty miles high above the Great Ocean, a north polar projection at one-to-one scale.
That explained how Norton was able to relate one-to-one with the role players here-they were living forward, while he was living backward-for him.
There is a mutual confrontation of games, of realities 'where you live', which is quite different from the essentially seclusive and permissive 'ear' in one-to-one therapies.
He graduated from Shippensburg State College (now Shippensburg University), and his first job after graduation was in the Appalachian Poverty Program, where he was expected to counsel and tutor underprivileged children on a one-to-one basis.
Whatever this thing is, it's syncing up and shadowing our team in a one-to-one matchup, and like you said, the mating ritual is giving it additional energy—topspin.
Alp appreciated the guards' tactical problem: on a one-to-one basis the Uigurs were supreme.
Huber adjusted his sight picture onto the leftmost caret, enlarging the central portion around the pipper while the surrounding field remained one-to-one so that he wouldn't be blindsided by an unglimpsed danger.
By the same token, the meaning of a telegram that we send does not stand in any one-to-one relation with the properties of the electromagnetic waves of the wireless telegraph.