What is the US English for "soppy"?

Solution 1:

Initially, I assumed that the AmE sappy was merely a varied spelling of the BrE soppy. However, tchrist alerted me to some difficulties with that assumption and, in fact, according to etymonline, soppy (originally) was in reference to the quality of excessive wetness (and in AmE: sopping or soaking wet), while sappy appears to be a reference to tree sap. Despite their disparate origins, it seems the two words have evolved to share the sense of excessive sentimentality.

sappy adjective

3a: overly sweet or sentimental

3b: lacking in good sense: silly

(Merriam-Webster online)

soppy (adj.) "very wet," 1823, from sop + -y (2). Meaning "sentimental" first recorded 1918. Related: Soppiness.

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). (etymonline)

sap (n.2) "simpleton," 1815, originally especially in Scottish and English schoolboy slang, probably from earlier sapskull (1735), saphead (1798), from sap as a shortened form of sapwood "soft wood between the inner bark and the heartwood" (late 14c.), from sap (n.1) + wood (n.); so called because it conducts the sap; compare sappy. (etymonline)

Solution 2:

I think you are looking for the word saccharine which is defined below:

excessively sweet or sentimental.