'slender'(Modern English slight)
This adj. < PGmc *slixta- is common throughout Gmc (cp. Goth slaíhts 'smooth, even', OFris sliucht 'simple', OS sliht 'decorated, ornamented', OHG sleht 'smooth, mild'), but does not occur as a simplex in OE, while OIcel sléttr 'plain, flat, even, smooth, level' (< earlier ON *sleht-) is very common. That said, a native adj. *sliht 'even' can be plausibly reconstructed (as e.g. AEW) on the basis of an adv. eorðslihtes (adv.) 'close to the ground'. The sense 'slender' (MED and OED sense 2) is rare in ME.
Proposed ON Etymon (OIcel representative)
sléttr 'plain, flat, even, smooth, level'
(ONP sléttr (adj.))
Other Scandinavian Reflexes
Far slættur, Icel sléttur, Norw slett, ODan slæt, Dan slet, Sw slät, Sw dial sljett
cp. eorðslihtes (adv.) 'close to the ground'
Phonological and morphological markers
Relatively infrequent in ME, and attested mainly from N/EM texts (though more widespread in MED's surname material).
Occurrences in the Gersum Corpus