present participle of challenge

Difficult, hard to do.

The act of making a challenge.

A system of organizations, people, technology, activities, information and resources involved in moving a product or service from supplier to customer.

(intransitive) To haggle or barter. / (transitive) To buy. / To talk much and idly; to chatter.

bargaining; merchandise

(agriculture) The upper sieve of a cleaning shoe in a combine harvester, where chaff is removed

(medicine) a pressurized vessel used to administer oxygen at elevated pressure

(chiefly UK) A reclining chair with a long seat, which can support the outstretched legs of a sitter normally with one armrest.

(Britain, New Zealand, idiomatic) Said of things that very different, though possibly superficially alike.