is a specific kind of: longness.

is a broader term that covers: coextension.

derivation: draw out, extend, prolong, protract.

is a specific kind of: duration, length.

is a broader term that covers: fermata.

derivation: continue | draw out, extend, prolong, protract | carry on, continue, go on, proceed | continue, keep, keep on, retain | keep up, prolong, sustain | continue, go along, go on, keep, proceed | continue, remain, stay, stay on | continue | drawn-out, extended, lengthy, prolonged, protracted.