hằng số thời gian 
time constant [ hằng ] : (1) usually, habitually; (2) the Moon
[ số ] : (1) amount, number, figure, quantity, size (of clothing), digit, edition; digital; (2) gear (of a car); (3) destiny, fate, lot
[ thời ] : time(s), era
[ gian ] : (1) dishonest, underhanded, tricky; (2) apartment, room; (3) difficult, hard; (4) danger, peril
Most Common Compounds Set 1:
Most Common Compounds Set 2 :
hằng số thời gian siêu quá độ subtransient time constant