A narrow sheet placed crosswise on the bed under the patient to assist in moving the patient or in changing soiled bed coverings.
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n.
a sheet placed beneath a patient in bed that, when one portion has been soiled or becomes uncomfortably wrinkled, may be pulled under the patient so that another portion may be used. The bed does not have to be remade, and the patient does not have to leave bed.
Medical dictionary. 2011.