at one time
1. At the same time; in unison. Don't try to carry more than two boxes at one time—they're heavy! I can't understand a word with all of you screaming at one time.
2. In the past. Yes, I was a teacher at one time, long before I became a fashion designer.
at one time
1. Simultaneously, at the same time, as in All the boys jumped into the pool at one time. For synonyms, see at once, def. 1; at the same time, def. 1.
2. Formerly, in the past, as in At one time very few houses in town were on the market.
at one time
1. Simultaneously.
2. At a period or moment in the past.