groundlessly

• 凭空捏造

  fabricate without evidence

• 凭空想象

  imagine groundlessly

• 凭空指责

  reprimand without cause

• 凭空冤枉人

  accuse people wrongly without cause

• 这不是凭空说的。

  This was not said without cause.

• 这不是凭空想出来的。

  This was not thought up without any evidence.