1 to pile up

2 to heap up

3 a mass

4 pile

5 heap

6 stack

7 large amount

1 garbage heap

1 to pile up

1 to pile up

2 to heap

3 accumulation

1 to gather together

1 lit. piles of work and papers (idiom); fig. accumulated backlog of work

1 to pile up like a mountain (idiom)

2 a mountain of (paperwork etc)

3 a large number of sth

1 to dig into piles of outdated writings (idiom); to study old books and papers