xanri -xar- gismu

x1 [concept] exists in the imagination of/is imagined by/is imaginary to x2.

Also (adjective:) x1 is mental (one sense), x1 is unreal (one sense); in spite of the synonym, note that x1 is imaginary does not imply that it doesn't exist in the real world; the definition is crafted so that one can talk about imaginary things without claiming that they thereby don't exist. See also fatci, senva, sucta, zasti, cfika, dacti, menli, sidbo.

In notes:

cfika
x1 is a work of fiction about plot/theme/subject x2/under convention x2 by author x3.
dacti
x1 is a material object enduring in space-time; x1 is a thing.
fatci
x1 (du'u) is a fact/reality/truth/actuality, in the absolute.
menli
x1 is a mind/intellect/psyche/mentality/[consciousness] of body x2.
senva
x1 dreams about/that x2 (fact/idea/event/state); x2 is a dream/reverie of x1.
sidbo
x1 (idea abstract) is an idea/concept/thought about x2 (object/abstract) by thinker x3.
sucta
x1 (si'o) is abstracted/generalized/idealized from x2 [something concrete] by rules x3.
zasti
x1 exists/is real/actual/reality for x2 under metaphysics x3.
cumselpei
x1=p2=c1 (subject/concept) is conceivable under conditions c2.
selxanri
xa2 imagines xa1.
selxarkei
k1=x2 pretends x1[concept]
xarpei
p1 = x2 imagines / visualizes imaginary subject / concept p2 = x1.
xarpresmitra
x1=t1=s1 acts like/pretends to be fictional/imaginary character x2=t2=s2=xa1=p1 imaginary to x3=xa2, in property/way x4=s3 under conditions x5=t3.