one-to-oneadv.adj.n.
/ˌwʌntəˈwʌn/, U.S. /ˈwən(t)əˈwən/ A. adv.
With or in direct contact between two individuals. Now also (frequently in Mathematics and Logic): as or by means of a one-to-one correspondence (see sense B. 2).
ΘΚΠ
the world > relative properties > relationship > correlation > [adverb] > one-to-one, etc.
one-to-one1581
one-on-one1992
1581 A. Hall tr. Homer 10 Bks. Iliades iii. 48 Their chargings oft, their cruel fight, their meetings one to one,..made for hir loue alone.
1611 J. Florio Queen Anna's New World of Words Fólla..a course in the field where many horsemen or tilters, after they haue runne single one to one, they runne pell mell altogether.
1840 R. H. Dana Two Years before Mast xix. 193 They are a match for the dog,—one to one,—but as the dogs generally went in squads, there was seldom a fair fight.
1903 B. Russell Princ. Math. xi. 113 Two classes have the same number..when their terms can be correlated one to one, so that any one term of either corresponds to one and one only term of the other.
1963 J. Lyons Struct. Semantics iii. 37 It is not so much that one language draws a greater or less number of semantic distinctions than another which prevents the matching of their vocabularies one-to-one.
1995 New Scientist 11 Feb. 51/2 The number of points in a sphere is what is known as an ‘uncountable infinity’, meaning that the points cannot be matched one-to-one with the whole numbers 1,2,3 [etc.].
1998 Daily Tel. 16 Oct. 24/2 Kundalini combines prolonged breath suspension and a stable posture with intense meditative concentration. Best practised one-to-one.
B. adj.
1. Denoting equal proportions or numbers of two things, or a ratio of 1:1.
ΚΠ
1869 H. S. Osborn Metall. Iron & Steel 19 For the sake of brevity, the one-to-one proportion is called the one-oxide, or protoxide, and the other the one-and-a-half oxide.
1927 F. A. E. Crew Genetics of Sexuality in Animals vii. 151 All the individuals of this generation will be normal in genetic constitution and so will yield a succeeding generation exhibiting a normal one to one ratio.
1968 R. C. Lewontin Population Biol. & Evol. 2 It is a problem of population biology to discover under what circumstances a one-to-one sex ratio is evolved.
2001 B. Broady In this Block there lives Slag 133 Lottery funded, it would have a one-to-one staff-client ratio and was housed in a converted mansion.
2. Designating a correspondence or relation in which each member of one set, class, group, etc., is associated with or related to one member of another set, class, group, etc., and vice versa. Frequently in Mathematics and Logic: cf. one–one adj.2
ΘΚΠ
the world > relative properties > relationship > correlation > [adjective] > one-to-one, etc.
one-to-one1873
multivalent1891
one–many1901
one-for-one1908
many–one1910
one-to-many1916
many–many1922
many-to-one1964
many-to-many1981
1873 Proc. London Math. Soc. 4 252 The equations..being supposed to establish a ‘one-to-one’ correspondence between the two integral spaces.
1931 C. Fox Mind & its Body iii. 62 One of the most important assumptions of psychological physiology was this one-to-one correspondence between neural processes and mental processes.
1936 J. R. Kantor Objective Psychol. Gram. xvii. 237 There is no clear-cut one-to-one relation between a grammatical form and a definite time point.
1968 C. G. Kuper Introd. Theory Superconductivity xii. 193 There is a one-to-one correspondence between the states of a gas of non-interacting Bosons and those of a family of harmonic oscillators.
1996 J. H. Conway & R. K. Guy Bk. of Numbers x. 277 The precise definition is that two collections A and B give the same cardinal number just when there's a one-to-one correspondence between them.
3. Consisting of or involving face-to-face contact or direct communication between two individuals.
ΘΚΠ
the world > space > relative position > opposite position > [adjective] > facing > face-to-face
face-to-face1864
one-to-one1970
one-on-one1972
1970 New Society 5 Mar. 401/1 Group psychotherapy is based on ‘free floating discussion’, the equivalent in the group of ‘free association’ in the one-to-one psycho-analytic process.
1995 Daily Tel. 14 June 15/3 Only half the fathers questioned spend less than five minutes a weekday in one-to-one communion with their children.
2000 BookPage Oct. 33/4 Brazelton and Greenspan emphasize the need for daily, personal, one-to-one contact between parent and child.
C. n.
An instance of face-to-face interpersonal contact or direct communication between two people. Also: a sexual relationship between two people.
ΚΠ
1983 ‘J. le Carré’ Little Drummer Girl xviii. 297 ‘My chief said a one-to-one, if it's all the same to you.’... Litvak dropped back until he was out of earshot.
1994 D. Cappon Intuition & Managem. vii. 97 At that level, in one-to-ones and small groups, it doesn't matter whether the ‘product’ is economics or politics.
1998 Cosmopolitan (U.K. ed.) Aug. 129/1 He's more likely to say ‘thanks a lot’ and take your love lessons—together with the tie you bought him—straight into another one-to-one.
2001 FourFourTwo Sept. 96/1 Anyone can become a director or owner as long as they haven't had one of those tricky one-to-one's with the Department of Trade and Industry.
This entry has been updated (OED Third Edition, June 2004; most recently modified version published online March 2022).
<
adv.adj.n.1581