trough
noun [ C ]
uk/trɒf/ usa situation in which something has reached its lowest level, price, etc. before going up again:
Your monthly payments will smooth over any peaks and troughs in the price of the shares.
Growth in services slowed to its lowest since the trough of the recession.
trough
verb [ I ]
informal uk/trɒf/ usto reach a low level, price, etc. before going up again:
The economy troughed six months ago and is now growing again.