Martin-Bell syndrome
transitive set
Leyland number
clutter
xylanolysis
difference of two squares
H-space
Cartesian square
topological space
pronilfactor
fault
malfunction
trisomy X
vicious circle
formal power series
symptom
shemozzle
XXX
Jordan algebra
metaproblem
Cauchy problem
clusterfuck
fug
perplexity
congestee
uncompatibility
mavoglurant
orbit
degenerative disorder
equivalence gate
disarray
Markov number
XNAND
a kangaroo loose in the top paddock
consensus theorem
xenospecificity
xenogenicity
Dormand-Prince method
snag
can of worms
puzzle
design flaw
headfuck
bridal tree
mystifier
Sylvester equation
puzzler
teaser
perfect storm
FG syndrome