The phrase "time period" refers to a specific length or duration of time that is being referred to or discussed. It helps to define a specific timeframe or an interval of time. Full definition
Individual investors have only returned 2.5 percent in that same time period in large part due to fear. (gobankingrates.com)
For these four pairs, exchange rates for time period of up to 10 years can be obtained. (investopedia.com)
Moreover, using long time periods for averaging makes it impossible to avoid major volcanic eruptions, which involve uncertainty as to the large forcing excursions involved and their effects. (bishop-hill.net)