The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
Appendix I
Indo-European Roots
ENTRY:
genu-1
DEFINITION:
Knee; also angle. Oldest form *enu-, becoming *genu- in centum languages. 1. Variant form *gneu-.a.knee, from Old English cno, knee, from Germanic *knewam;b.kneel, from Old English cnowlian, to kneel, from Germanic *knewljan.2. Basic form *genu-.geniculate, genuflect, from Latin gen, knee. 3. O-grade form *gonu.polygonum, pycnogonid, from Greek gonu, knee. 4. Suffixed variant form *gnw-y-.–gon, gonion; amblygonite, diagonal, goniometer, orthogonal, from Greek gni, angle, corner. (Pokorny 1. enu- 380.)
enu-, becoming *genu- in centum languages. 1. Variant form *gneu-. a. knee, from Old English cn
o, knee, from Germanic *knewam; b. kneel, from Old English cn
, knee. 3. O-grade form *gonu. polygonum, pycnogonid, from Greek gonu, knee. 4. Suffixed variant form *g
nw-y
-. –gon, gonion; amblygonite, diagonal, goniometer, orthogonal, from Greek g
, angle, corner. (Pokorny 1. 
