opening
empty area

do as directed

round inward

brief
to the point

degree viscosity
how
thick and thin liquid

dependent

shape
outline of a shape

distinct
separate

limp
lacking tone

likely to occur soon

so gradual
as to not become apparent for long time

changing rapidly and often

nervous system

nervous system and blood system.

obvious
easily observed.

signficantly important
dangerous
parameter
characteristic
constant factor
limit

beginning suddenly
abruptly
convulsive