Meaning of “smooth” - Learner’s Dictionary

smooth

adjective uk us /smuːð/
SURFACE

B1 having a regular surface that has no holes or lumps in it:

soft, smooth skin
a smooth wooden table
SUBSTANCE

B1 A substance that is smooth has no lumps in it:

Mix the butter and sugar together until smooth.
MOVEMENT

happening without any sudden movements or changes:

The plane made a smooth landing.
PROCESS

happening without problems or difficulties:

Her job is to help students make a smooth transition from high school to college.
PERSON

too polite and confident in a way that people do not trust:

a smooth salesman
smoothness noun [ U ]

(Definition of “smooth adjective” from the Cambridge Learner’s Dictionary © Cambridge University Press)