Which is correct – ‘biologic’ or ‘biological’, ‘histologic’ or ‘histological’, ‘physiologic’ or ‘physiological’? Is there a difference or can these words be used interchangeably?

Opinions regarding the use of the –ic and –ical word endings are varied and conflicting, and this issue has been hotly debated in linguistics and lexicology (Kaunisto, 2007). In 1969, the linguist Hans Marchand promoted the use of the shorter ‘-ic’ form, stating that this form was more closely linked to the root meaning of the word because it is a derivative of the noun form, whereas the ‘-ical’ form is more loosely related because it is a derivative of the adjectival form and thus more general. The 18th century linguist James Elphinston argued that the ‘-ic’ form was used more for “solemn” subjects and the ‘-ical’ form, for more “familiar” subjects. This led Marchand to comment that the ‘-ic’ form is more common in science due to its conciseness. That is, “the scholar uses the unextended forms much more, as for him the quality expressed by the adjective is more directly and intimately connected with the thing to which it [the word] is applied than it is for a non-scientist” (as cited in Kaunisto 2007 p.25).

The authoritative gold-standard reference for editing in the life sciences, Scientific Style and Format, the Council of Biology Editors Manual for Authors, Editors and Publishers (6th edition), states that the shorter form is generally preferred, whereas the most recent the Scientific Style and Format, the Council of Science Editors Manual for Authors, Editors and Publishers (8th edition – note the name change from Biology to Science), simply states that the use should be consistent throughout a particular document. In British English, the “-ical” form is more commonly used than in American English.

The AMA Manual of Style (10th edition) states that a dictionary (e.g., Merriam-Webster Collegiate, Stedman’s, Dorland’s, American Heritage, Oxford English) should be consulted for selecting the correct suffix for an adjectival form of a word, and that “the ‘-ical’ form is more remote from the word root and may have a meaning beyond that of the ‘-ic’ form” (AMA Manual of Style, 10th edition, accessed online September 7, 2015). Like the Scientific Style and Format, the Council of Science Editors Manual for Authors, Editors and Publishers, the AMA Manual of Style states that the most important aspect is to use the terms consistently throughout the article, chapter, or publication, but that “… usually the ‘-al’ may omitted unless its absence changes the meaning of the word.”

Be aware, however, that the selection of the correct suffix depends on which dictionary you consult. Merriam-Webster’s Online dictionary (accessed September 7, 2015) states that ‘physiologic’ is a variant of ‘physiological’. Dorland’s Illustrated Medical Dictionary (28th Edition) states that ‘physiologic’ means “normal; not pathologic; characteristic of or conforming to the normal functioning or state of the body or a tissue or organ; physiological (p. 1290) ”, while ‘physiological’ means “pertaining to physiology; physiologic (p. 1290)”. Note that these two words have different primary definitions, but are also considered variants as secondary definitions.

Choosing between variants of some words is especially confusing, e.g., ‘biologic’, ‘biological’, and ‘biologics’. In Dorland’s ‘biologic’ and ‘biological’ are variants that mean “pertaining to biology (p. 199)” and can be used interchangeably. ‘Biologicals’, however, means “medicinal preparations made from living organisms and their products, including serums, vaccines, antigens, antitoxins, etc. (p. 199)”. On the other hand, the current Merriam-Webster Online dictionary defines ‘biologic’ as a “biological product (as a vaccine or blood serum) used in medicine (http://www.merriam-webster.com, accessed September 7, 2015). Therefore, biologic can be considered a variant of ‘biologics’ or ‘biological’. In the end, it comes down to the context of the writing. In a report on the treatment of rheumatoid arthritis, ‘biologic’ will likely mean a biological product, whereas in a report on protein structure, biologic will likely mean ‘as pertaining to biology’.

Today, both forms are commonly found in scientific writing. At SciTechEdit International, our editors generally use the shorter, more classic ‘-ic’ form, with some exceptions: in manuscripts written in UK English and when the client has expressed a specific preference, and, of course, when the context calls for more in-depth consideration of the most applicable variant.

References
Kaunisto, M. (2007) Variation and Change in the Lexicon: A Corpus-based Analysis of Adjectives in English ending in –ic and –ical. Editions Rodopi BV; Amsterdam. ISBN: 978-9042022331.

Dorland’s Illustrated Medical Dictionary (28th edition) W.B. Saunders Co., Philadelphia, 1994.

Merriam-Webster Online Dictionary, http://www.merriam-webster.com, accessed September 7, 2015.

Scientific Style and Format, the Council of Biology Editors Manual for Authors, Editors and Publishers (6th edition); Cambridge University Press, 1994.

Scientific Style and Format, the Council of Biology Editors Manual for Authors, Editors and Publishers (8th edition); University of Chicago Press, 2014

AMA Manual of Style (10th edition); Oxford University Press, 2007