Stock that is sold without a warrant attached to it. Warrants let the owner buy stock at a future date at a specific price, which typically is below the market price.  Ex refers to the trading of shares when a warrant has been declared but not distributed.  It trades without the right to receive the warrant, without the warrant attached. 
For example a warrant may permit its owner to purchase ten shares of stock at $20.00 per share up to a specified date and then at $22.50 per share thereafter until the warrant expires. 
From document conveying authority" (1510s).