In English grammar and morphology, doublets are two distinct words derived from the same source but by different routes of transmission, such as poison and potion (both from the Latin potio, a drink). Also known as lexical doublets and etymological twins. When the two words are used together in a phrase they are called coupled synonyms or binomial expressions.

Three words of this kind are called triplets: e.g., place, plaza, and piazza (all from the Latin platea, a broad street).

Examples and Observations

- "English has many doublets from Latin sources. Usually the earlier word came from Norman French and the later one came from central French . . . or directly from Latin. Occasionally we have three words, or a triplet, from the same source, as in cattle (from Norman French), chattel (from central French), and capital, all derived from the Latin capitalis, meaning 'of the head.' Another example is hostel (from Old French), hospital (from Latin), and hotel (from modern French), all derived from the Latin hospitale."

- (Katherine Barber, Six Words You Never Knew Had Something to Do With Pigs. Penguin, 2007)

- "It is no coincidence that the basic meaning of adamant was 'diamond.' The word diamond is a doublet of adamant, the two words having come ultimately from the same Greek source, adamantos.

- "The present-day adjective, meaning 'unyielding, inflexible,' usually in the phrase to be adamant, is first recorded in the 1930s. It was apparently an extended use of such earlier phrases as an adamant heart (1677), meaning 'a heart of stone' and adamant walls (1878) 'stone walls.'"

- (Sol Steinmetz, Semantic Antics. Random House, 2008)

Cadet, Caddie, Cad

"In Medieval Gascon French, a capdet was a 'little chief, little head,' from the Late Latin capitellus, a diminutive form of Latin caput 'head.' The term was originally applied specifically to a 'younger son of a nobleman, serving as a military officer at the French court,' . . .. The term passed into Standard French in this Gascon sense, but later was generalized to mean 'younger (son, brother).'

"In the 17th century, French cadet passed into English, which reworked the French meanings and, in the process, created the doublet form caddie.

During the 17th and 18th centuries cadet was used to mean 'junior military officer,' while caddie meant 'military trainee.' The 18th century also saw the creation of the abbreviated form cad, which seems to have had a variety of senses, all of them suggesting assistant status: 'assistant to a coach-driver, wagoner's helper, bricklayer's mate,' and the like."

(L. G. Heller et al., The Private Lives of English Words. Taylor, 1984)

Differences in Meaning and Form

- "Doublets vary in closeness of meaning as well as form: guarantee/warranty are fairly close in form and have almost the same meaning; abbreviate/abridge are distant in form but close in meaning (though they serve distinct ends); costume/custom are fairly close in form but distant in meaning, but both relate to human activities; ditto/dictum share only di and t and a common reference to language; entire/integer are so far apart that their shared origin is of antiquarian interest only." (Tom McArthur, The Oxford Companion to the English Language. Oxford University Press, 1992)

Doublets in Legal Language

"[David] Mellinkoff (1963: 121-2) indicates that many . . . legal terms appear in company--they are routinely used in sequences of two or three (doublets are also known as 'binomial expressions' and 'binomials').

. . . Everyday words can be transformed into legal formulae in this way. Melinkoff also points out that many doublets and triplets combine words of Old English/Germanic (OE), Latin and Norman French origins.

Examples of doublets

of sound mind (OE) and memory (L)

give (OE) devise (F) and bequeath (OE)

will (OE) and testament (F/L)

goods (OE) and chattles (F)

final (F) and conclusive (L)

fit (OE) and proper (F)

new (OE) and novel (F)

save (F) and except (L)

peace (F) and quiet (L)