off-peak
adjective [ before noun ]
uk/ˌɒfˈpiːk/ us/ˈɒfˈpiːk/not at the most popular and expensive time, when many people are doing or using a particular thing:
off-peak phone calls
off-peak train times
off-peak hours
Off-peak fares are cheaper prices for travelling on trains that are less busy.
off-peak
adverb
It's cheaper to travel off-peak.