1. If there is a Latin adjective ending with -abilis, the corresponding
English one ends with -able. If not, use one of the following rules
(which so far as I can see always give the same result):
2. use "atable" if and only if the verb in "ate" is stressed on its
last syllable.
3. use "atable" if and only if the verb in "ate" has fewer than three
syllables.
Evidence:
mutable, conjugable, explicable according to the Oxford English
Dictionary (second ed 20 vols) are all from L. -abilis, however
rotatable, translatable, dilatable, datable, integrable, differentiable
according to OED are all from English verbs in -ate + -able or -ble.
(All those Engl. verbs come from Latin verbs or past participles.)
However, is OED right? Did anyone writing in Latin before 1727 (the first
English use of "integrable" in OED) use "integrabilis" or before 1863
"differentiabilis"?
John Harper, School of Mathematical and Computing Sciences,
Victoria University, Wellington, New Zealand
e-mail john.harper@vuw.ac.nz phone (+64)(4)471 5341 fax (+64)(4)495 5045