亶
タン, セン, あつ.い, ほしいまま
truly, wholly, cordial
JLPT0 G13 S0 F5000
As per 旦# (long and flat) + a granary (compare the top element of 稟) → the long and flat foundation of a storehouse → *thick* (← thick foundation). *True*, *truly* and *selfish/selfindulgent* are borrowed meanings.
[Full Kanji Etymology List]