advisory body; think tank
A group of advisors or experts that provides counsel, often in political, business, or organizational contexts. Can refer to a formal advisory panel or a research-oriented think tank.
The government set up an advisory body for the new policy.
The think tank made recommendations on economic reform.
シンクタンク is a direct loanword for 'think tank' and is commonly used in modern contexts, whereas 顧問団 may sound slightly more traditional or institutional.
military advisory group
Compound of 顧問 (komon, 'advisor') and 団 (dan, 'group'). The exact historical derivation is uncertain, but the word follows a common pattern for naming organized groups.