-ect and -igible

[eldin raigmore]

Several English verbs that end with -ect, have associated adjectives that end with -igible.
Examples:
correct —> corrigible
direct —> dirigible
elect —> eligible
neglect —> negligible

Note that all of my examples have a liquid phoneme (an <l> or an <r>) immediately before the vowel that starts the ending.
Is this a general rule in English? Does English have any “-ect -igible” pairs that aren’t “-lect -ligible” nor “-rect -rigible”?

[Salmoneus]

It's not really useful to talk about a 'general rule' to govern just a handful of words.

I can't think of any other examples, but the 'rule' is obviously just a coincidence. Such an alternation would only occur in a very small number of verbs in English (those derived from a Latin root verb in -egere), and then only a minority of those would be sufficiently commonplace to maintain the alternation rather than levelling it (or else would happen to have the alternation reinforced by borrowing from French). They'd also have to have been borrowed as verbs in the first place (a lot of -ct verbs are just borrowed from the participle form and then verbed, so never had the -g- forms to begin with).

All your examples are just of two Latin verbs that happen to have liquids in them: legere and regere. In theory there's a few other words that could take -gible form and in some pedantic way they'd be valid English words (eg protect > protigible), and of course since every Latin word is an English word in sufficiently hifalutin speech you could in theory create some, like "adact" (something hurled or driven, assuming -act is close enough for you) > "adigible" (something hurlable). But I can't think of any in common usage.

Best obscure pair off the top of my head that might have been recorded somewhere: crucifect > crucifigible. Google tells me Burnet used the term 'crucifect' at least once; it can't find anything for 'crucifigible', but I'd certainly guess that someone, somewhere in English literature has used it, even if only jocularly...

[k1234567890y]

1. I don't think these rules are productive in English, for example, we have collect -> collectible instead of **colligible; besides, we have neglectable and correctable alongside with negligible and corrigible.

2. Note that all the four words are ultimately from Latin, and all of them are formed with either the root of legō, legere (“I pick up, select, gather, etc.”) or the root of regō, regere (“I rule, make straight, steer, etc.”), and at least correct, corrigible, dirigible, eligible are borrowed through French, so it can be a reflection of how learned people tried to create words by exploiting their knowledge in Latin(and some of these people might not speak English), instead of a reflection of a forgotten rule of English.