Kikigender is an aesthetigender based on the bouba/kiki effect  - specifically the shape that is more commonly assigned the name 'kiki'. This gender is sharp, pointy and definite. It is also associated with a high density, gender dysphoria and being gender frictive.
The opposite of kikigender is boubagender.
The word 'kiki' is the adjectival form of kikigender. To say that something is 'kiki' is to say that it has some of the qualities of a kikigender but is not necessary kikigender. For example "My pupgender gender is very kiki."
This term was coined by Fenryr from the Obsidian System in a discord server called xenos and co on the 20th of December, 2021. 
The original bouba/kiki effect was first observed on the island of Tenerife by Wolfgang Köhler in 1929 using the words "takete" and "baluba" to assign names to two shapes. This experiment was repeated in 2001 by Vilayanur S. Ramachandran and Edward Hubbard who asked American college students and Tamil speakers to assign two shapes the name "bouba" or "kiki". "In both groups, 95% to 98% selected the curvy shape as "bouba" and the jagged one as "kiki", suggesting that the human brain somehow attaches abstract meanings to the shapes and sounds in a consistent way." [Wikipedia, 2021.]