What is the definition or description of: atelectasis?

Atelectasis: Atelectasis (from greek: ἀτελής, "incomplete" + ἔκτασις, "extension") is defined as the collapse or closure of the lung resulting in reduced or absent gas exchange. It may affect part or all of one lung. It is a condition where the alveoli are deflated, as distinct from pulmonary consolidation. It is a very common finding in chest xrays which needs to be interpreted in the face of clinical symptom.

Atelectasis refers: To collapse of alveoli upon themselves, such that they are no longer capable of effectively participating in gas exchange (uptake of o2 and release of co2). It is frequently seen at the bases of the lungs in cxrs because the tissue is more dense than aerated lung. It's clinical significance depends upon the circumstances of the patient in whom it is detected. If you need more details, just ask.

Atelectasis=: collapse of a lung or part of a lung from a variety of causes.