Last week, I wrote a passage about persimmons. There I put a word 渋み（しぶみ） in brackets as the translation of bitterness.
“Bitter” is usually translated as 苦い（にがい） in Japanese. However, the bitterness in persimmons is usually described as 渋い（しぶい）（苦い and 渋い are both an いadjective. Their noun form is 苦み and 渋み respectively）.
渋い to describe a flavour is one of the Japanese words that are very difficult to translate into English. My dictionaries say “astringent” and/or “acerbic” but neither of them sounds right to me. When you have a 渋い food like 渋柿（しぶがき, bitter persimmons）, the whole mouth feels almost numb for a while. In order to understand the feel, it may be easiest if you try a bitter persimmon!?
The word 渋い can also be used to describe other things, such as:
渋い声（しぶいこえ）= a nice low voice
渋い演技（しぶいえんぎ）= low-key performance of actors
渋い顔（しぶいかお）= a sour face
Anyway, I will wrap up this post by introducing a tongue twister with the word persimmons （柿、かき）in it:
隣の客はよく柿食う客だ（となりのきゃくはよくかきくうきゃくだ, the neighbour’s guest is a guest who eats lots of persimmons. ）
Let me know how well you can say that!