The Cambridge Guide to Australian English Usage - Noel's ESL ...

ibex
Baconiana: certain genuine remains of Sir Francis Bacon, arguments civil and
moral ...
Nowadays the suffix is usually understood to mean publications about a particular
author or culture, and is extended to cover archival material and even antique
objects.
ibex For the plural of this word, see under -x.
ibid. This referencing device is an abbreviated form of the Latin ibidem meaning
“in the same place”. Used in follow-up references to a particular book, chapter or
page, it directs readers to the same source or place as was mentioned in the preceding
reference. It substitutes for the author’s name, the title of the book or article, and
as much of what follows as would be identical. For example:
1 Hardy, C. “A family line” Australian Journal of Genealogy 3 (1952), p. 85
2 ibid. p. 92
The reference with ibid. must come immediately after the full one: if not the followup
reference must repeat the author’s name or an abbreviated title. (See further
under referencing.) Ibid. could once appear in the main body of text, but its use
has steadily declined and is nowadays confined to footnotes and endnotes.
-ibility or -ability See -ability.
-ible See under -able/ -ible.
-ic/-ical Quite a number of English adjectives appear in two forms, for example:
analytic/analytical
arithmetic/arithmetical
astronomic/astronomical
egotistic/egotistical
fanatic/fanatical
ironic/ironical
magic/magical
monarchic/monarchical
mystic/mystical
obstetric/obstetrical
parasitic/parasitical
philosophic/philosophical
poetic/poetical
problematic/problematical
psychic/psychical
rhythmic/rhythmical
Is there any reason for preferring one over the other?
The short answer is no: many pairs do not differ significantly in meaning. But
there are shades of difference in some, such as comic(al), electric(al) and lyric(al),
discussed under their respective headings. Typically the -ic spelling corresponds
more closely to the core meaning of the stem, while the meaning of the -ical spelling
is rather generalised. In yet others such as economic(al), historic(al) and politic(al),
the meanings diverge considerably (see individual headwords).
In past centuries (from the fifteenth to the seventeenth) there were many more
such pairs derived from classical sources:
grammatic(al) identic(al) organic(al) tragic(al)
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