If it knowledge, then the last one should be sik1
Also, for jyutping ji1 would pronounce as 衣
ji1 sik6 sounds like 衣食, and mou4 ji1 sik6 sounds like 無衣食 (no clothes & food??)
Still, such a term can't be related to ungratefulness.
Actually, if the poster is quite sure about the last syllable,
then there's only a handful of characters for choice, most of which are about eating:
蝕 食 射 吃 喫
[jyut.net]
Also, for jyutping ji1 would pronounce as 衣
ji1 sik6 sounds like 衣食, and mou4 ji1 sik6 sounds like 無衣食 (no clothes & food??)
Still, such a term can't be related to ungratefulness.
Actually, if the poster is quite sure about the last syllable,
then there's only a handful of characters for choice, most of which are about eating:
蝕 食 射 吃 喫
[jyut.net]