Something that's demanding calls for more work or skill than the typical task. Babysitting might seem like an easy job, but depending on the kids it can actually be incredibly demanding.
A demanding job might require a lot of physical work, like farming, or a lot of patience and diplomacy, like being a teacher or a marriage counselor. When a person is described as demanding, it usually means that he or she has very high standards or is especially hard to satisfy. The word comes from the Old French demander, "to request or demand," by way of the Latin demandare, "entrust."
adj requiring more than usually expected or thought due; especially great patience and effort and skill
requiring precise accuracy
hard to please, hard-to-please
(of persons) "his father was a hard-to-please taskmaster"
demanding or needing attention, affection, or reassurance to an excessive degree
rigorous, stringent, tight
demanding strict attention to rules and procedures
exacting, stern, strict
severe and unremitting in making demands
not easy; requiring great physical or mental effort to accomplish or comprehend or endure