focus on tent in the word.. when the wind blows into the tent,it expands or appears swollen.. out of shape appearance
detention centre will make you swollen out of shape
distention= extent(tent) act of(tion)root word so act of extending with pressure within baloon
dis + TENSION. U get tension when u think beyond or much.. which we can also be spoken as stretched beyond..
tention(tension): when we get tensed we will be pressurised