This is the 6361st most frequent Japanese word.
シケ
"シケ" means "rough seas" or "stormy weather" at sea.
In this context, 'シケ' refers to stormy or rough weather at sea.
海が荒れていて、今日はシケだ。
The sea is rough, it's stormy weather today.
Here, 'シケる' derived from 'シケ' can mean to have bad or undesirable conditions.
試合の日に限って毎回シケるなんて、嫌になる。
It’s frustrating how the weather turns bad every time it's game day.
In this usage, 'シケた' means gloomy or down, extending its use metaphorically from stormy conditions.