A problem that is challenging to solve.
Used other than figuratively or idiomatically: see hard, nut, crack.
A situation, person, group, etc. which is difficult to overcome or deal with.
A place, opportunity, etc. to which it is difficult to gain entry.
An amount that is difficult to finance.
A difficult or tedious undertaking.
Any piece of work done.
A process or execution of a program.
An objective.
A piece of work done as part of one’s duties.
To charge, as with a fault.
To assign a task to, or impose a task on.
To oppress with severe or excessive burdens; to tax