noun
single chopstick stuck upright in rice offered to the deceased
A Japanese funeral custom: a single chopstick is placed vertically in a bowl of rice as an offering to the dead. This practice is strongly taboo in everyday dining.
葬儀では、故人に一本箸を立てたご飯を供える。
At a funeral, a bowl of rice with a single chopstick stuck upright is offered to the deceased.
食事中に箸を一本だけご飯に突き刺すのは一本箸と呼ばれ、縁起が悪いとされる。
Sticking a single chopstick upright into rice during a meal is called ippon-bashi and is considered unlucky.
葬儀 means funeral ceremony; 一本箸 is a specific ritual object used in that context.
Compound of 一本 (ippon, 'one long slender object') and 箸 (hashi, 'chopstick'), with rendaku voicing of hashi to bashi. The term directly describes the object used in the funeral rite.