Pile up Definition 1 of 3Pro Tip 1/3Time reference Use when indicating that tasks or items are gathering gradually. The emails pile up if I don't check my inbox regularly. Pro Tip 2/3Feeling overwhelmed Describes the stress from a growing number of tasks or problems. When assignments pile up, I feel overwhelmed. Pro Tip 3/3Contextual use Often used in work or administrative contexts to describe backlog. Leave requests tend to pile up around the holidays.