noun, noun or participle which takes 'suru', intransitive verb
partaking; participating; sharing in
Often used in the phrase 相伴にあずかる, meaning to be invited to share in a meal or experience. Can also be used more broadly for joining in an activity or benefit.
夕食を相伴にあずかった。
I was invited to share in their dinner.
彼の成功の相伴にあずかりたい。
I want to share in his success.
参加 is a general word for participation in events or groups, while 相伴 implies sharing in something, often with a nuance of being invited or included in a benefit.
The exact derivation is uncertain; the kanji 相 (mutual) and 伴 (accompany) suggest the idea of accompanying each other, which aligns with the meaning of sharing or partaking.