"resembling or consisting of meal," 1530s, from meal (n.2) + -y (2). From 1560s as "covered with fine dust or powder;" 1590s as "containing meal;" 1704 as "covered with flour." Related: Mealiness.
Entries linking to mealy
meal n.2
"the edible part of ground grain;" Middle English mēle, from Old English melu, from Proto-Germanic *melwan "grind" (source also of Old Frisian mele "meal," Old Saxon melo, Middle Dutch mele, Dutch meel, Old High German melo, German Mehl, Old Norse mjöl "meal;" literally "what is ground;" Old Saxon, Old High German, Gothic malan, German mahlen "to grind"), from PIE root *mele- "to crush, grind." The verb form is not found in Old English. Forms with an -a- begin in late Middle English. "Now commonly understood to exclude the product of wheat (this being called FLOUR)" [OED].
-y 2
adjective suffix, "full of or characterized by," from Old English -ig, from Proto-Germanic *-iga- (source also of Dutch, Danish, German -ig, Gothic -egs), from PIE -(i)ko-, adjectival suffix, cognate with elements in Greek -ikos, Latin -icus (see -ic). Originally added to nouns in Old English; used from 13c. with verbs, and by 15c. even with other adjectives (for example crispy). Adjectives such as hugy, vasty are artificial words that exist for the sake of poetical metrics.