Sappy

wiktionary

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From Middle English sappy, sapy, from Old English sæpiġ(“full of sap, succulent”), equivalent to sap +‎ -y. Cognate with West Frisian sappig(“juicy”), Dutch sappig(“juicy, succulent”), Middle High German saffic, seffec("juicy, succulent"; > German saftig), Danish saftig(“juicy”), Swedish saftig(“juicy”). Doublet of zaftig.

Compare Latin sapere(“to taste”).

etymonline

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sappy (adj.)

"full of sap," Late Old English sæpig, from sæp (see sap (n.1)). Figurative sense of "foolishly sentimental" (1660s) may have developed from an intermediate sense of "wet, sodden" (late 15c.). Earlier, now obsolete, figurative senses were "full of vitality" (1550s) and "immature" (1620s).