A Word, Please: Able to the task

Every time I see a promo for the movie “The Expendables,” I do a double-take. The “-ables” ending looks wrong to me.

So I picture the name spelled “Expendibles,” which, of course, looks even worse. That’s because the producers are spelling it correctly. “Webster’s New World College Dictionary” lists “expendable,” with an A, as an adjective meaning “that can be expended.”

The question of when to end a word with “-able” and when to end it with “-ible” confounds a lot of people, from eBay sellers who push collectibles while spelling them “collectables” to anyone who says some expense is “deductable” when he meant it is “deductible.”

Why do incalculable, immovable and noticeable take A, while irresistible, incorrigible and negligible take I? It’s the kind of stuff that makes new English learners throw their hands up in despair. This issue can drive even a grammar columnist nuts. I know because when I began to research -ables and -ibles, I found myself wading through a swamp of confusing and contradictory advice.

“Garner’s Modern American Usage” calls -able a “living suffix,” but says that “-ible is no longer a combining form in English.”

A bona-fide suffix can combine with another word to create a brand-new compound that isn’t in the dictionary but is nonetheless legitimate. A clappable performance. A spoonborne virus. A cubiclewide policy. A ferretlike man. You probably won’t find these in your dictionary or your spellchecker, but they’re legitimate because they follow a legitimate formula: Real word plus real suffix equals legitimate word.

So because -able is a real suffix, you can attach it to just about any verb to make your own adjective. Kissable, discardable, walkable, writable, knowable, keepable — the rules governing suffixes make these all acceptable.

But if, as Garner says, -ible is no longer a real suffix combinable with other words, then it’s not like -able. You can’t tack in on to verbs of your choice to create words like kissible, discardible, walkible, knowible, writible and keepible.

Then what, you ask, is -ible doing in words like legible, collectible, edible, visible, permissible, credible, compatible and digestible? Those aren’t compounds you assemble yourself. They’re bona-fide words, sanctioned by the dictionary. And if the dictionary spells it with an -ible, that’s the way to go.

So Garner’s advice creates a neat little distinction between -able and -ible that I would love to rely on if it weren’t for one little problem: Many dictionaries say that -ible is indeed a suffix, just as -able is. Some call -ible a “variant” of “-able,” which tells us they don’t like it as much. But because they include it as a real suffix, we know that we can’t take Garner’s analysis as gospel.

But we can take it as a guideline. Whenever you’re grappling with -able vs. -ible, look the word up in a dictionary. If your word is in there with either spelling, just spell it as listed. If it’s not in the dictionary, you can attach your own -able. That’s always a safe choice. Just don’t be too quick to criticize someone who opts for an -ible because, with many dictionaries, you could argue it’s justified.

And here’s a handy tip for identifying many common -ible words: If you chop off the -ible ending, what’s left often is not a whole word. That is, take “edible,” “possible,” “permissible,” “feasible,” “compatible” or “terrible,” delete the ending, and you’re left with “ed,” “poss,” “permiss,” etc.

Those aren’t the same as the complete verbs you get when you chop “-able” off “doable,” “reasonable,” “allowable,” etc. But don’t rely on this as a litmus test, or you could end up misspelling “digestible.”

The lesson here is that, even though English may seem unmasterable, its challenges are never insurmountable.

JUNE CASAGRANDE is author of “It Was the Best of Sentences, It Was the Worst of Sentences.” She can be reached at JuneTCN@aol.com.