silent partner 
noun
North American term for sleeping partner.The other 15% of the firm is owned by four silent partners, who invested another $10,500 in seed money for a total of $70,000 in start-up costs....
- Keep in mind, however, that individual investors tend to be silent partners, which could be good or bad, depending on your needs.
- Her evidence was that the business was ready to go by March 2001, and that she was going to be the active partner, and her son-in-law would be the silent partner.