The word "lame-brains" is an informal term used to describe someone who is unintelligent or foolish. However, there are various synonyms that can also be used to convey the same meaning. Some of these synonyms include the words "idiot," "moron," "fool," "dolt," "dimwit," "simpleton," or "blockhead." These terms can be used interchangeably depending on the context in which they are being used. It is important to note that using these words as insults can be hurtful and offensive, so it is always better to use them cautiously and with consideration for others.