rheum noun¹. [ru:m] Now chiefly arch. LME.
[Old French reume (mod. rhume) from late Latin rheuma bodily humour, flow from Greek, from rhein to flow.]
1. A watery substance secreted by a mucous membrane, esp. as collecting in or dripping from the nose, eyes, etc. Formerly also, (a flow of) any abnormal, harmful, or unhealthy moisture or 'humour' (freq. fig.). LME.
b. collect. sing. Tears. poet. L16.

2. spec. A mucous discharge caused by infection with a cold. Also, a cold in the head; catarrh. Usu. in pl. LME.

[TahlilGaran] English Dictionary ▲

rheum noun². ['ri:ǝm] M18.
[mod. Latin (see below), from Greek rhēon. Cf. RHUBARB noun & adjective.]
A plant of the genus Rheum, of the knotgrass family; a rhubarb.

[TahlilGaran] English Dictionary ▲