a sleeping mat: the thin, portable pad a poor or bedridden person lies on, light enough to roll up and carry away
This is not a bed with a frame. It is bedding: a stuffed pad or rough mattress laid straight on the floor, the sort of thing a day laborer slept on and a sick person was carried on. Every time the New Testament uses the word, it belongs to someone poor, ill, or both:
- a paralyzed man lowered through a torn open roof on it (Mark 2:4)
- villagers hurrying their sick out to Jesus on them (Mark 6:55)
- a man at a pool in Jerusalem told to pick his up and walk (John 5:8)
- the sick laid out in the street so Peter's shadow might fall on them (Acts 5:15)
- Aeneas, who had lain on his for eight years (Acts 9:33)
The word itself was common speech. It came into Greek from Latin, and ancient teachers of polished Greek listed it among the words a careful writer should avoid. Mark uses it five times anyway. Telling the same healing, Matthew reaches for the ordinary word for a bed (κλίνη) and Luke for a tidier word meaning a small couch (κλινίδιον). The object is the same in all three accounts; what differs is how plainly each writer names it.
That plainness does real work in the stories. A mat can be picked up, which is why the command keeps coming out as "get up, take your mat, and walk": the man who had to be carried now carries the thing that carried him, in front of everyone. In John 5 that same detail starts an argument, because hauling a load through the streets was exactly what the Sabbath rules forbade.