False cognates are pairs of words that seem to be cognates because of similar sounds and meaning, but actually have different etymologies; they can be within the same language or from different languages. That is different from false friends, which may in fact be related but have different meanings.
As an example of false cognates, the Spanish word haber sounds and looks similar to the English word have, but are in fact unrelated.
The term "false cognate" is sometimes misused to refer to false friends, but the two phenomena are distinct. False friends occur when two words in different languages or dialects look similar, but have different meanings. While some false friends are also false cognates, many are genuine cognates (see False friends § Causes). For example, English pretend and French prétendre are false friends, but not false cognates, as they have the same origin. A related phenomenon is the expressive loan, which looks like a native construction, but is not.
"Mama and papa" type
The basic kinship terms mama and papa (together with the wider class of Lallnamen) comprise a special case of false cognates. The striking cross-linguistical similarities between these terms are thought to result from the nature of language acquisition. According to Jakobson (1962), these words are the first word-like sounds made by babbling babies; and parents tend to associate the first sound babies make with themselves and to employ them subsequently as part of their baby-talk lexicon. Thus, there is no need to ascribe the similarities to common ancestry. This hypothesis is supported by the fact that these terms are built up from speech sounds that are easy to produce (nasals like [m] or [n], typically for "mother" words, or plosives like [p], [b], [t], [d], typically for "father" words, along with the low vowel [a]). However, variants occur; for example, in Old Japanese, the word for "mother" was papa, and in Slavic languages, baba is a common nickname for "grandmother", as in Baba Yaga and babushka. In Georgian, the usual pattern (nasal for "mother", plosive for "father") is inverted: the word for "father" is mama, and the word for "mother" is deda.
- English sheriff and Arabic sharif, both legal officers
- English ache and Ancient Greek ἄχος (ákhos) (pain, distress)
- English ask and Jaqaru aska
- English bad, Persian bad, and Armenian vad (ւադ) (bad)
- English be and Gbaya be 
- English chill, chilly and Quechua chiri, chili "cold"
- English cut and French couteau "knife"
- English day, daily and Spanish día, or Latin dies, or Italian dì, or even English diary
- English "dog" and Mbabaram "dog"
- English dung and Korean 똥 ttong (excrement)
- English emoticon and Japanese 絵文字 emoji
- Arabic anta and Japanese anata 'you'.
- English hollow and Lake Miwok hóllu
- English tiny and Yana tʼinii
- English see and Assyrian Neo-Aramaic zee (see)
- English occur and Japanese okiru
- English mount and Hawaiian mauna
- English cut and Hindi kaṭ
- English -s (plural ending) and French and Spanish -s (plural ending)
- English base and German böse (evil)
- French feu (fire)[note 1] and German Feuer (fire)[note 2]
- German haben and Latin habere (both "have")
- Greek root -lab- and Sanskrit root -labh- (take)
- Inuktitut kayak and Turkish kayık
- Malay mata and modern Greek máti (eye, from ommátion)
- Malagasy vorona "bird" and Russian vorona "crow"
- Hindi "sant" and English "saint"
- Japanese oi (おい) and British English oi (Interjection to get someone's attention)
- Japanese miru (見る) and Spanish mirar (to watch)
- Japanese nomu and Tagalog inum.
- Latin deus, Greek theos and Nahuatl teotl, all meaning 'god'
- Serbo-Croatian macan "tom-cat" and Indonesian / Javanese macan "panther"
- False friend
- Phono-semantic matching
- Folk etymology
- False etymology
- Semantic change
- Etymological fallacy
- Convergent evolution
- from Latin focus
- from Proto-Germanic *fūri
- Moss (1992), p. ?.
- Chamizo-Domínguez (2008), p. 166.
- Harper, Douglas. "Pretend". The Online Etymological Dictionary. Retrieved 2015-09-14.
- Harper, Douglas. "ache". Online Etymology Dictionary. Douglas Harper. Retrieved 29 August 2014.
- Lyle Campbell, Historical Linguistics: An Introduction, 3rd edition, p. 350
- Oxford English Dictionary, Second edition.
- Martin, Samuel E. (1966). "Lexical Evidence Relating Korean to Japanese". Language. 42 (2): 187. doi:10.2307/411687.
- Taggart, Caroline (5 November 2015). "New Words for Old: Recycling Our Language for the Modern World". Michael O'Mara Books – via Google Books.
- Lyle Campbell, Historical Linguistics: An Introduction, 3rd edition, p. 355
- Online Etymology Dictionary
- LIV s. v. *sleh₂gʷ-, *lembʰ-
- de la Fuente, José Andrés Alonso (2010). "Urban legends: Turkish kayık 'boat' and "Eskimo" Qayaq 'Kayak'" (PDF). Studia Linguistica Universitatis Iagellonicae Cracoviensis. Retrieved 2015-03-06.
- Chamizo-Domínguez, Pedro J. (2008), Semantics and Pragmatics of False Friends, New York/Oxon: Routledge
- Jakobson, Roman (1962), "Why 'mama' and 'papa'?", Selected Writings, I: Phonological Studies, The Hague: Mouton, pp. 538–545
- Moss, Gillian (1992), "Cognate recognition: Its importance in the teaching of ESP reading courses to Spanish speakers", English for Specific Purposes, 11 (2): 141–158, doi:10.1016/s0889-4906(05)80005-5
- Rubén Morán (2011), 'Cognate Linguistics', Kindle Edition, Amazon.
- Geoff Parkes and Alan Cornell (1992), 'NTC's Dictionary of German False Cognates', National Textbook Company, NTC Publishing Group.