Sentence:  to <WSD>pack</WSD> a joint;  to <WSD>pack</WSD> the piston of a steam engine;  <WSD>pack</WSD> someone's arm with ice. 
Meaning of the word marked with <WSD> tags:  To render impervious, as by filling or surrounding with suitable material, or to fit or adjust so as to move without giving passage to air, water, or steam.