Is it possible to use something similar to the English suffix "-able" to show that the action described can be done by someone or something? If not, what phrases do you suggest to use in its place?
As brianpck mentioned, the English suffix "-able" is borrowed from Latin. The rules for applying it in Latin are more transparent than the English alteration between "-able" and "-ible". EDIT: And are actually even easier, now that I think about it.
First, choose your stem.
- If the verb has a fourth principal part (supine) ending in -tus, remove the -tus and use that stem: amō, amātus > amā-
- If it has a fourth principal part not ending in -tus, add an -i and use that stem: rideō, rīsus > rīsi-
- Otherwise (e.g. posse), use the present infinitive stem (poss-)
If this stem already ends in -bi, attach -lis: habi- > habilis, nūbi > nūbilis > nubile.
- These would originally have been habibilis and nūbibilis; the -bibi- was reduced to -bi- by haplogy.
- Otherwise, attach -bilis.
All of the resulting adjectives are regular two-termination thirds: -ilis, -ilis, -ile.
My previous, overly complicated, explanation:
If the present stem ends in a vowel (including v and j), add -bilis: mov- > mōbilis > mobile
- This can cause diphthongs to contract (ov → ō), since they're followed by a consonant
- Usually vowel-stem verbs are obvious, but some are trickier; the stem of fleō is fle- rather than fl- (and thus it becomes flēbilis)
- If the verb is first-conjugation, attach -ābilis to the present stem: am- > amābilis, dūr- > dūrābilis > durable.
- Otherwise, attach -ibilis...
- If the fourth principal part ends with -tus, or there is no fourth part, use the present stem: crēd- > crēdibilis > credible, poss- > possibilis > possible
- Otherwise, use the supine stem: rīd- > rīsibilis > risible, vid- > vīsibilis > visible
There are also a few exceptions to these rules: for instance, stō, stāre > stăbilis rather than *stābilis. But *stābilis would still be easily understood.
(The more complicated rules worked, but there's no reason to memorize them if you already know the supine stem. Using the supine also eliminates "irregularities" like stăbilis from stō, stătus and flēbilis from fleō, flētus.)
The English suffix "-able/-ible" comes directly from Latin -abilis/-ibilis.
A search for Latin words ending in -bilis returns 737 results, of which the first few are:
This might have been better as a comment, but I think it worth an answer to link generally to other answers and comments.
The University of British Columbia publishes an excellent introduction to this general kind of thing for both Latin and Greek at https://pressbooks.bccampus.ca/greeklatinroots/front-matter/preface/, where the linked page has a table of further linked contents. Chapter 5 is on 'Turning Latin Nouns into Adjectives', within which para. 34 discusses adjective-forming suffixes in English, while 35 and onwards give examples of endings and their derivation (including -ilis, -arius and -osus.)