The word "oilygrains" is spelled as /ˈɔɪliˌɡreɪnz/. The first part of the word, "oily," is spelled with the digraph "oi," which represents the diphthong sound /ɔɪ/. The second part of the word, "grains," is spelled with the consonant digraph "gr," which represents the sound /ɡr/. The final syllable, "-ains," is spelled with the letter "a" followed by the consonant digraph "in," representing the sound /eɪn/. Together, the word refers to grains or seeds with a high oil content.
The seeds of te sesamum, an Eastern grainplant which contains abundance of oil.
Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.