As nouns the difference between fast and planking
is that
fast is (british|rail transport) a train that calls at only some stations it passes between its origin and destination, typically just the principal stations or
fast can be the act or practice of abstaining from food or of eating very little food while
planking is a series of planks; a group of planks.
As verbs the difference between fast and planking
is that
fast is to abstain from food, or eat very little, especially for religious or medical reasons while
planking is .
As an adjective fast
is (dated) firmly or securely fixed in place; stable.
As an adverb fast
is in a firm or secure manner, securely; in such a way as not to be moved.
As an interjection fast
is (archery) short for "stand fast", a warning not to pass between the arrow and the target.