Wiktionary
n. (context linguistics English) A pair of words differing by only one phonetic segment or suprasegment, used to prove the validity of a proposed phoneme, toneme, or chroneme.
Wikipedia
In phonology, minimal pairs are pairs of words or phrases in a particular language that differ in only one phonological element, such as a phoneme, toneme or chroneme, and have distinct meanings. They are used to demonstrate that two phones constitute two separate phonemes in the language.
Many phonologists in the middle part of the 20th century had a strong interest in developing techniques for discovering the phonemes of unknown languages, and in some cases setting up writing systems for these languages. The major work of Kenneth Pike on the subject has the title Phonemics: a technique for reducing languages to writing. The minimal pair was an essential tool in the discovery process, arrived at by substitution or commutation tests. Modern phonology is much less interested in such issues, and the minimal pair is consequently considered to be of little theoretical importance.
As an example for English vowels, the pair "let" + "lit" can be used to demonstrate that the phones (in let) and (in lit) do in fact represent distinct phonemes and . An example for English consonants is the minimal pair of "pat" + "bat". The following table shows other pairs demonstrating the existence of various distinct phonemes in English. All the possible minimal pairs for any language may be set out in the same way.
word 1
word 2
IPA 1
IPA 2
note
pin
bin
initial consonant
rot
lot
thigh
thy
zeal
seal
bin
bean
vowel
pen
pan
hat
had
final consonant
Phonemic differentiation may vary between different dialects of a language, so that a particular minimal pair in one accent is a pair of homophones in another. This does not necessarily mean that one of the phonemes is absent in the homonym accent; merely that it is not contrastive in the same range of contexts.