In linguistic morphology, a cranberry morpheme (or fossilized term) is a type of bound morpheme that cannot be assigned an independent meaning or grammatical function, but nonetheless serves to distinguish one word from the other.
|Look up cranberry, mulberry, gooseberry, raspberry, or blackberry in Wiktionary, the free dictionary.|
The archetypal example is the cran of cranberry. It is unrelated to the word cran meaning a case of herrings, and though it actually comes from crane (the bird), this is not immediately evident. Likewise, mul exists only in mulberry (mul is from Latin morus, the mulberry tree). Phonetically, the first morpheme of raspberry also counts as a cranberry morpheme, even though the word "rasp" does occur by itself. Compare these with blackberry, which has two obvious unbound morphemes, and to loganberry and boysenberry, whose first morphemes are derived from personal names.
Other cranberry morphemes in English include:
- mit in permit, commit, transmit, remit, and submit, from the Latin verb mittere  meaning to give, to send
- ceive in receive, perceive, and conceive, from the Latin verb capere  meaning to seize
- twi in twilight
- cob in cobweb, from the obsolete word coppe for a spider
Cranberry morphemes can arise in several ways:
- A dialectal word can become part of the standard language in a compound, but not in its root form: e.g. blatherskite, "one who talks nonsense", has Scots skite meaning "contemptible person".
- A word can become obsolete in its root form but remain current in a compound: e.g. lukewarm from Middle English luke "tepid".
- A compound loanword may have a recognisable native cognate for one element but not the other: e.g. hinterland is from German hinter "behind" and land "land".
- A loanword may have one part misanalysed to a false cognate: e.g. a taffrail is a type of rail, but the word comes from Dutch tafereel "carved panel".
- "Cranberry morpheme" from the Lexicon of Linguistics 
- Definition of mittere from Wiktionary
- Compare French mettre, an unbound morpheme and -cevoir, which is also a cranberry morpheme.
- Definition of capere from Wiktionary