die off phrasal verb (see also die)
if a group of people or animals die off, they die one by one until there are no more of them

[TahlilGaran] Dictionary of Contemporary English ▲

die off
to die one after another until no members of a particular group are left.
She was ninety-two and said all her friends had died off.

[TahlilGaran] English Idioms Dictionary ▲

die off
to die one after another until the number is small
The house plants began to die off as soon as we moved to a new apartment.

[TahlilGaran] English Idioms Dictionary ▲

die off
v. To die one at a time.
The flowers are dying off because there has been no rain.

[TahlilGaran] English Idioms Dictionary ▲