dekad

Borrowed from Ancient Greek δεκάς (dekás, “group of ten”). By surface analysis, deka- +‎ -ad. Doublet of decad and decade.

dekad (plural dekads)

1. (climatology) Ten days, especially of rainfall. Generally identified as dekad 1: 1^st-10^th, dekad 2: 11^th-20^th, and dekad 3: 21^st-last day of each month.
   • 2022 July 1 (last accessed), “Africa InterTropical Front (ITF)”, in Climate Prediction Center‎^[1], NOAA, archived from the original on 1 July 2022:

     Figure 1 displays the current position of the ITF relative to the long-term average position during the 2nd dekad of June and its previous position during the 1st dekad of June.

• pentad

From English decade, from Middle English, from Middle French decade, from Late Latin decas (“(set of) ten”), from Ancient Greek δεκάς (dekás), from δέκα (déka, “ten”).

• IPA^(key): /ˈdekad/ [ˈde.kat̪̚]
• Rhymes: -ekad, -ad
• Hyphenation: de‧kad

dékad (plural dekad-dekad or dekad²)

1. decade (a period of ten years)

• dékadê (Indonesian)

• "dekad" in Pusat Rujukan Persuratan Melayu (PRPM) [Malay Literary Reference Centre (PRPM)] (in Malay), Kuala Lumpur: Dewan Bahasa dan Pustaka, 2017