The word "ericoid" is used in modern biological terminology for its literal meanings and for extensions. Etymologically the word is derived from two Greek roots via Latin adaptations. Firstly, the Ancient Greek name for plants now known in English as "heather" was "ἐρείκη", believed to be Latinised by Pliny as "Erica". Linnaeus, who predominantly wrote in Latin, used Erica as the name of the genus which still is known as such.
However, when Linnaeus named an organism, using a specific epithet that described it as being like some particular thing, he commonly did so by appending the suffix "—οειδης". That was a contraction of "—ο + ειδος", denoting a likeness of form. In its Latinised form it became: "—oides". An example is the entry 9413 Stilbe ericoides according to Wappler's Index Plantarum to Linnaeus' "Species Plantarum". Further derivations emerged at need or convenience, such as "—oidea".
Accordingly, ericoid could have more than one meaning and it has been misapplied from time to time in the literature. For example, sometimes a writer uses it where the correct word would be "ericaceous", meaning a member of, or related to, the family Ericaceae. More precisely ericoid means "resembling an Erica" in some relevant way. In practice the commonest use is in reference to a plant's habit, in particular its leaves. The term is not precise, but "ericoid leaves" is a convenient way to describe small, tough (sclerophyllous) leaves like those of heather. Applied to a plant, ericoid generally means that apart from its sclerophyllous leaves, it has short internodes so that the leaves more or less cover the usually slender branchlets.
- Brown, Lesley (1993). The New shorter Oxford English dictionary on historical principles. Oxford [Eng.]: Clarendon. ISBN 0-19-861271-0.
- Gledhill, David (2008). The Names of Plants. Cambridge University Press. p. 156. ISBN 978-0-521-86645-3.
- Jaeger, Edmund Carroll (1959). A source-book of biological names and terms. Springfield, Ill: Thomas. ISBN 0-398-06179-3.
- Linnaeus, Index Plantarum quae continentur in Linnaeani Systematis. Printed Christian Friedrich Wappler, Vienna 1785
- Jackson, Benjamin, Daydon; A Glossary of Botanic Terms with their Derivation and Accent; Published by Gerald Duckworth & Co. London, 4th ed 1928
- Collocott, T. C. (ed.) (1974). Chambers Dictionary of science and technology. Edinburgh: W. and R. Chambers. ISBN 0550132023.