篤
トク, あつ.い
fervent, kind, cordial, serious, deliberate
JLPT1 G7 S16 F1942
竹
# (rigid) bamboo + 馬 horse → startled horse (compare 驚) standing rigid in attention → *be attentive* (← thoroughness) → *cordial*; *kind*.
[Full Kanji Etymology List]