Ever wonder why we have words like sing when the past tense is sang, but other words like talk that have a past tense with the suffix -ed? Here’s why…
A little background: a primary derivation makes words using roots (that aren’t really words themselves) and a secondary derivation makes words based off of words that already exist in a language.
In proto Indo European (PIE), a lot of roots had the form of CVC (consonant-vowel-consonant), with the V being interchangeable with different vowels to create different words.
Ablaut refers to when vowels alternate inside the root.
Example: The root l_g in Greek exists. Within the space, vowels can alternate to create different words, such as logos (n. word) and legein (v. to speak). If I’m correct, Arabic is another example of a language that has this feature.
If you see things like sing (v.), sang (v. past tense), and song (n.), then it’s a native English word. Another example of this includes sit/sat and run/ran.
These are all primary derivations.
Secondary derivations don’t have the ablaut feature, so these verbs have their past tenses with the suffix -ed that we all know and love.
*sed- (PIE) –> sit (present) & sat (past)
setl (Old Eng. “seat”) –> settle (present) & settled (past)
Here, setl is a primary derivation, and settle is a secondary derivation. Because settle is a secondary derivation, its past tense is settled with the -ed suffix.