Posted by Bruce Kahl on April 04, 2004
The official spelling is Daylight Saving Time, not Daylight SavingS Time.
Saving is used here as a verbal adjective (a participle). It modifies time and tells us more about its nature; namely, that it is characterized by the activity of saving daylight. It is a saving daylight kind of time. Similar examples would be "dog walking time" or "book reading time". Since saving is a verb describing a single type of activity, the form is singular.
Nevertheless, many people feel the word savings (with an 's') flows more mellifluously off the tongue, and Daylight Savings Time is also in common usage, and can be found in dictionaries.