family members; insiders; close associates
Refers to people within one's own close circle, such as family, relatives, or a trusted in-group. Often used when contrasting with outsiders.
We gathered as close family and friends and held a small dinner party.
Please keep this story a secret just among us insiders.
身内 is a more common word for 'family' or 'relatives,' while 内輪同志 emphasizes the insider/outsider distinction and can include close non-family members.
内輪 alone can mean 'private' or 'within the family,' but 内輪同志 specifically refers to the people themselves as a group.
Compound of 内輪 (uchiwa, 'family circle; private') and 同志 (dōshi, 'comrades; fellows'). The exact historical derivation is uncertain, but the combination naturally yields the meaning 'fellow insiders.'