Schlei·den 
(shlīdn), Matthias Jakob 1804-1881.
(shlīdn), Matthias Jakob 1804-1881. German botanist who studied the cell nucleus and proposed that all tissues in plants are composed of cells.
- underwood
- underwool
- underworld
- under wraps
- underwrite
- underwriter
- undescended testicle
- undeserved
- undeservedly
- undesigning
- undesirability
- undesirable
- undesirably
- undetermined
- undid
- undies
- undifferentiated
- undignified
- undine
- undiplomatic
- undiplomatically
- undirected
- undiscriminating
- undisposed
- undisputed