The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
Appendix I
Indo-European Roots
ENTRY:
sek-
DEFINITION:
To cut. Derivatives include scythe, Saxon, skin, insect, and sickle. 1.scythe, from Old English sthe,sigthe, sickle, from Germanic *segith, sickle. 2. Suffixed o-grade form *sok--.saw1; hacksaw, from Old English sagu,sage, saw, from Germanic *sag, a cutting tool, saw. 3. Suffixed o-grade form *sok-yo-.sedge, from Old English secg, sedge, from Germanic *sagjaz, “sword,” plant with a cutting edge. 4. Suffixed o-grade form *sok-so-.a.zax, from Old English seax, knife, from Germanic *sahsam, knife, sword; b.Saxon, from Late Latin Sax (plural Saxons), a Saxon, from West Germanic tribal name *Saxon-, Saxon, traditionally (but doubtfully) regarded as from Germanic *sahsam (as if “warrior with knives”). 5. Extended root *skend-, to peel off, flay. skin, from Old Norse skinn, skin, from Germanic *skinth-.6. Basic form *sek-.a.secant, –sect, sectile, section, sector, segment; dissect, insect, intersect, resect, transect, from Latin secre, to cut; b.seecatch, from Russian sech', to cut. 7. Lengthened-grade form *sk-.sickle, from Latin scula, sickle. 8. Possible suffixed variant form *sak-so-.sassafras, saxatile; saxicolous, saxifrage, from Latin saxum, stone (< “broken-off piece”?). (Pokorny 2. sk- 895, sken-(d-) 929.) See also extended roots skei-, sker-1.
the, sigthe, sickle, from Germanic *segith
, sickle. 2. Suffixed o-grade form *sok-
-. saw1; hacksaw, from Old English sagu, sage, saw, from Germanic *sag
s), a Saxon, from West Germanic tribal name *Saxon-, Saxon, traditionally (but doubtfully) regarded as from Germanic *sahsam (as if “warrior with knives”). 5. Extended root *skend-, to peel off, flay. skin, from Old Norse skinn, skin, from Germanic *skinth-. 6. Basic form *sek-. a. secant, –sect, sectile, section, sector, segment; dissect, insect, intersect, resect, transect, from Latin sec
k- 895, sken-(d-) 929.) See also extended roots skei-, sker-1. 
