underestimate the real value or ability of; "Don't sell your students short--they are just shy and don't show off their knowledge"
sell securities or commodities or foreign currency that is not actually owned by the seller, who hopes to cover (buy back) the sold items at a lower price and thus to earn a profit
having or showing great excitement and interest; "enthusiastic crowds filled the streets"; "an enthusiastic response"; "was enthusiastic about taking ballet lessons"
(law) compulsory pretrial disclosure of documents relevant to a case; enables one side in a litigation to elicit information from the other side concerning the facts in the case