Assimilated Prefixes
📋 What it is
A prefix sometimes CHANGES its last letter to match the root it joins — this is assimilation. "in-" (not) becomes im- before p/b/m, il- before l, ir- before r: impossible, illegal, irregular.
🗣️ Coach says
The prefix is being polite — it shifts a letter so the word rolls off the tongue. "in + legal" would be clunky, so it smooths to "illegal". Same meaning (not), friendlier sound.
🧠 Memory hook
in- (not) → im- (before p/b/m) · il- (before l) · ir- (before r). Same meaning.
😂 Giggle
Why was "tele" such a good communicator?
It always reached far!
😲 Whoa!
That is why we say "irresponsible" not "inresponsible" — the "n" slid into an "r" to match the root, centuries ago, and stuck.
✅ Quick check: The prefix "in-" means "not". Why is it spelled "im-" in "impossible"?
Say your answer out loud first — then reveal.
It assimilated — "in-" changes to "im-" before p/b/m to match the sound, but it still means "not".
Recognizing an assimilated prefix stops you from missing a "not" hidden by a changed letter.
🧪 Try it! (2 minutes)
Add "in-" (not) to "legal", "regular", and "mature" — spell each correctly (il-, ir-, im-).