Definitions

1. superlative adjective

most late or slow in arriving or departing, or in doing something

“The tardiest member of the group was the last to arrive at the meeting.”

2. noun

the most late or slow of people, things, or events

“The team’s tardiest player was benched in the final game.”

3. adjective

being the most late or slow

“The tardiest bus of the day was still running late.”