In this part of the series, we'll go over all the words that refer to a specific point in time - days, tomorrow, next week, months and so on.
gestern, heute, morgen, Jahr, Monat, letzte, nächste
The core idea of this root was:
letting go, slacken off, relenting
And we can still see this sense in the English offspring, like last, let, lenient, latter or late.
By the way, the words relax and and release, though they would fit in here, apparently come from a different root.