triangle is kirolki

kirolki = triangle (shape) (noun) (some things Google found for "kirolki": a very rare term; user names; appears on a number of Polish websites; in Basque similar kirol means sport; in Finnish somewhat similar kirota means to curse, swear)

Word derivation for "triangle" :
Basque = hiruki, Finnish = kolmio
Miresua = kirolki

Another Basque word for triangle is triangelu.

Both the Basque word and the Finnish word appear to be derived from their language's word for three. (Three in Basque is hiru, three in Finnish is kolme.) My Miresua word for triangle somewhat resembles the Miresua word for three, kire.

The word triangle doesn't occur in Alice's Adventures in Wonderland or Through the Looking-glass.

square is nelki (revisited)

nelki = square (shape) (noun) (some things Google found for "nelki": a uncommon term; an unusual last name; a rare first name; user names; means cloves in Silesian which is language of Poland or a dialect of Polish; similar nelk means cloves in Estonian; Nelki's Place is a hotel in Lagos, Nigeria)

Word derivation for "square" :
Basque = lauki, Finnish = neliö
Miresua = nelki

My previous Miresua word for square was nölai.

The Basque word lauki does mean square, but translates to quadrilateral, 4-sided polygon. I found another word in Basque, karratu, that specifically means square. Although I chose to use the Basque word lauki again because, like the Finnish word, neliö, it's derived from its language's word for four. (Four in Basque is lau, four in Finnish is neljä.) I made my new Miresua word for square resemble the Miresua word for four, nelu.

The word square doesn't appear in Alice's Adventures in Wonderland. But square (and squares) appears numerous times in Through the Looking-glass.

For some minutes Alice stood without speaking, looking out in all directions over the country -- and a most curious country it was. There were a number of tiny little brooks running straight across it from side to side, and the ground between was divided up into squares by a number of little green hedges, that reached from brook to brook.

circle is pyrku (revisited)

pyrku = circle (shape) (noun) (some things Google found for "pyrku": a rare term; user names; a very rare last name; Bad OCR of old text documents; word I can't translate on some Polish language webpages; similar Pyrke and Pyrko are unusual last names; similar Pyrki is the name of a place in far eastern Russia)

Word derivation for "circle":
Basque = zirkulu, Finnish = ympyrä
Miresua = pyrku

I'm redoing this word. My previous word for circle was zumyrä, which was an alphabetic scramble, plus it ended in Ä. I'm trying to reduce the number of nouns ending in A or Ä. Under my rules, it's allowable to make the Miresua word one letter shorter than the shortest source word. In this case, that's one letter shorter than the Finnish word, which is a six letter word.

The y in Miresua is pronounced as in Finnish, as u in French or ü in German.

There is only one occurrence of the word circle in Alice's Adventures in Wonderland, in Chapter 3 - A Caucus-Race and a Long Tale.

First it marked out a race-course, in a sort of circle, ("the exact shape doesn't matter," it said,) and then all the party were placed along the course, here and there.

round is bipöri

bipöri = round (shape) (adjective) (some things Google found for "bipori": a rare term; user names; seems to mean biopore in Indonesian; similar Biporo is the name of a place in the Solomon Islands)

Word derivation for "round" (circular or cylindrical):
Basque = biribil, Finnish = pyöreä
Miresua = bipöri

I found the word round numerous times in Alice's Adventures in Wonderland, although all but three were in contexts which I, being an American, would have likely used the word around instead. This is a difference between British English and American English. Alice's author, Lewis Carroll, was a 19th century English writer.

Alice remained looking thoughtfully at the mushroom for a minute, trying to make out which were the two sides of it; and as it was perfectly round...

flat is lati

lati = flat (shape) (adjective) (some things Google found for "lati": a common term; LATI is an acronym for Lake Area Technical Institute of South Dakota; a unusual to uncommon last name; an unusual first name that can be feminine or masculine; Lati (aka White Wenge) is a species of wood from Africa; Café Lati in Seattle; LATI is an acronym for Los Angeles Taiko Institute which is a Japanese drumming school; Lati doll of South Korea sells collector dolls; in Italian lati means sides; in Latvian lati is the nominative plural of lats which was a former monetary unit of Latvia; similar Läti is the name of places in Estonia; name of places in Iran, Senegal, Afghanistan, Niger, the Philippines and Pakistan)

Word derivation for "flat" (having no variations in height):
Basque = lau, Finnish = litteä
Miresua = lati

I found the word flat twice in Alice's Adventures in Wonderland.

First came ten soldiers carrying clubs; these were all shaped like the three gardeners, oblong and flat, with their hands and feet at the corners...

This Miresua conlang word has been changed. The word for flat is now latä.

corner is izkuma

izkuma = corner (noun) (some things Google found for "izkuma": a rare term; user names which are often Japanese; in Serbo-Croatian similar iz Kuma seems to mean The Godfather)

Word derivation for "corner":
Basque = izkina, Finnish = kulma
Miresua = izkuma

There are other words in Basque and Finnish for corner. I think that these words are best for the meaning of corner, as in street corner.

The word corner appears four times (and corners once) in Alice's Adventures in Wonderland.

She was close behind it when she turned the corner, but the Rabbit was no longer to be seen...

song is abelu

abelu = song (noun) (some things Google found for "abelu": a uncommon term; a rare feminine first name that can be Norwegian; a rare last name; user names; ABELU is an acronym for Associação Beneficente Luterana (Charity Lutheran Association) in the state of Rondônia in Brazil; Abelu-Apaola seems to be a mountain in the Navarre region of Spain; name of a place in Mazandaran Province, Iran)

Word derivation for "song":
Basque = abesti, Finnish = laulu
Miresua = abelu

Another Basque word for song is kantu.

The word song appears seven times in Alice's Adventures in Wonderland.

'Twinkle, twinkle, little bat!
How I wonder what you're at!'

"You know the song, perhaps?"

"I've heard something like it," said Alice.

music is musiki

musiki = music (some things Google found for "musiki": an uncommon term; in Turkish another word for music in addition to the more common word müzik; user names; a rare last name; a very rare first name; similar Musikhi is the name of places in Russia)

Word derivation for "music":
Basque = musika, Finnish = musiikki
Miresua = musiki

For this word, I didn't have very much to work with.

The word music appears three times in Alice's Adventures in Wonderland.

...the Hatter said, tossing his head contemptuously. "I dare say you never even spoke to Time!"

"Perhaps not," Alice cautiously replied: "but I know I have to beat time when I learn music."