stab
/ˈstab/
noun
a wound produced by a pointed object or weapon
a thrust of a pointed weapon
a jerky thrust
verb
to wound or pierce by the thrust of a pointed object or weapon
thrust, drive
to thrust or give a wound with or as if with a pointed weapon
noun phrase
a guess that is based on very little or no information or evidence
an attempt that is not likely to succeed
They don't really know how much the work will cost. They're just taking a stab in the dark.