Underbed

(UNDER-¹ 5 b: cf. Du. onderbed, G. unterbett, Sw. underbädd.)

1648.  Hexham, II. Onder-bedde, an Vnder-bed.

1827.  Steuart, Planter’s G. (1828), 275. The thickness of the mass of roots and earth together, from the upper part of the collar, to the underbed of the roots.