the world > health and disease > ill health > be in ill health [verb (intransitive)] > be restrained by ill health (3)
Used simply = to ‘lie sick’, keep one's bed.
to keep one's bed: to remain in bed through sickness or other cause.
complex. to beor lie on one's back: to be laid up, to be afflicted; also, figurative to be prostrate, helpless; to lay any one on his back, to…