A moose is one moose. Two moose are two... moose. Not meese. Not mooses. Moose. You can have one goose and two geese, one mouse and two mice, one louse and two lice — but you cannot have two meese, two hice, or two spice (from spouse). The irregular plurals of English are a mess for a very specific historical reason, and it's not that English is chaotic — it's that English preserves just enough fragments of an older, more complex system to drive learners crazy.
The Umlaut Plural
In Old English, there was a productive way of forming plurals called "umlaut" (also called i-mutation). If a noun had a back vowel (like "oo" or "oh") in the singular, and the plural suffix contained a front vowel (like "i"), the back vowel in the root would be pulled forward to make the transition easier. Over time, the actual plural suffix was lost, but the vowel change remained. So "gōs" (goose) became "gēs" (geese) because of an ancient plural suffix that disappeared centuries ago. "Mūs" became "mȳs." "Lūs" became "lȳs." "Fōt" became "fēt." "Tōþ" became "tēþ." It was a regular rule at the time. Then the rule stopped being productive — meaning new words entering the language no longer followed it — but a handful of old words kept their umlaut plurals as linguistic heirlooms.
Why "Moose" Didn't Become "Meese"
This is the question that launched a thousand memes, and the answer is straightforward: timing. "Moose" was borrowed from Algonquian languages (probably Eastern Abenaki or a related language) sometime in the early 1600s, long after the umlaut plural rule had stopped being productive. By the time "moose" entered English, the default plural was -s (or no change for words ending in certain sounds). Nobody was going to apply an obsolete, fossilized vowel-change rule to a brand-new loanword from a completely different language family. "Moose" didn't become "meese" for the same reason your new smartphone doesn't come with a rotary dial — the technology had moved on.
The same logic explains "house" → "houses" (not "hice"). "Hūs" in Old English actually did have an umlaut plural form in some dialects, but it didn't survive into Modern English. The word "house" took the regular -s plural, like the vast majority of English nouns did. Some umlaut plurals won the evolutionary game; most lost. We remember the winners (geese, mice, feet) and forget the countless words that regularized. For every "tooth" that kept its vowel-change plural, there were dozens of words that gave up and went with -s. The survivors feel like rules; they're actually exceptions that refused to die.
The Plural System That Almost Wasn't
If history had gone slightly differently, English plurals might be entirely regular today. The -s plural (from Old English -as) started as just one of many plural endings. It spread because it was the plural ending of the dominant dialect — the Mercian dialect of the English Midlands, which became the basis for what we now call Standard English. If the West Saxon dialect had become dominant instead, we might all be forming plurals with -en ("one child, two children" — wait, that one's real) or with vowel changes, or with endings that would make English look more like German.
So the next time someone asks why it's "geese" but not "meese," you can tell them: the goose has been English for over a thousand years and remembers the old ways. The moose arrived 400 years ago and never learned them. Language, like culture, is just accumulated history pretending to be rules.