Smooth

glatt

(lacking friction, not rough)

glatt

(without difficulty)

glatt

(bland; glib)

glatt

(mathematics, of a function: Having derivatives of all finite orders at all points within the function’s domain)

problemlos

(without difficulty)

reibungslos

(without difficulty)

glätten

(make smooth)

glätten

(statistics: capture important patterns in the data, while leaving out noise)