to provide specifications for: Their newest truck was spec'd by a computer.
Idiom
5.
on spec, made, built, or done with hopes of but no assurance of payment or a sale; without commitment by a client or buyer: ad illustrations done on spec; luxury homes built on spec and sold before completion.
O.E. specca "small spot, stain," of unknown origin; probably related to Du. speckel "speck, speckle," M.Du. spekelen "to sprinkle." Meaning "tiny bit" developed c.1400.