KanjiJLPT N1
Fill In

fill in, fill up, make good

Mnemonic

You discover a pit of lies in the ground. To fill in the hole, you grab a spoon and scoop truth into it, one spoonful at a time. Each scoop of truth packs the gap tighter. Spoon after spoon, the truth fills in every crack until the ground is level and whole again.
Additional thoughts
Picture a comically small spoon being used to shovel heaps of glowing truth-material into a dark chasm. The contrast of the tiny utensil versus the massive hole makes it stick. Truth is the only substance dense enough to permanently fill in the void.
Quick recall
A spoon scoops glowing truth to fill in a gaping pit until the ground is perfectly level.

Details

The keyword for 塡 is fill in. This kanji refers to the act of filling in or stuffing something into a space, gap, or hole to make it complete or level. It conveys the idea of packing material into an empty area, whether literally filling in a ditch with earth or figuratively completing a blank space on a form. This is a traditional form of the more commonly seen 填, and both carry the same meaning of closing up gaps or making something whole by adding what is missing.
On'yomi
てん、ちん
Kun'yomi
はま.る、うず.める、は.める、ふさ.ぐ