Knowledge Bomb
Latin dissimilates liquids (r’s and l’s), and by virtue of our partitioned lexicon of classical and Germanic roots and affixes, we English speakers also dissimilate liquids and we’ve gone our whole lives without knowing it.
Exhibit A: The normal -al affix
- radial, regional, hysterical, labial, digital, lateral, tribal
Exhibit B: The -ar words
- polar (pole), solar, angular, particular, vehicular, uvular, popular, cellular
What unites the B set is the fact that -lal is a funny way to end those words, so -lar is chosen instead. This is what is meant by dissimilated liquids: -lar is chosen over -lal. In contrast, the A set (once sufficiently extrapolated) will contain all and only the -al endings that are not -lal. There might be a couple exceptions—lunar is an analogy of the dissimilated solar—but if you encounter a random Latinish word that ends in /l/ and you need to make a quick adjective from it, you will instinctively choose -ar over -al.
