1. at a time - Adverb
2. at a time - Phrase
simultaneously
Source: WordNetHow does a project get to be a year behind schedule? One day at a time. Fred Brooks
Dreams have only one owner at a time. That's why dreamers are lonely. Erma Bombeck
It is a mistake to look too far ahead. Only one link of the chain of destiny can be handled at a time. Winston Churchill
If you want to dismantle a hedge, remove one thorn bush at a time. Somali Proverb
One at a time is good fishing; two at a time is making a hog of yourself. American Proverb
At a time a cockerel matures, it begins to crow to tell the world the time of day. Nigerian Proverb