Also see the glossaries on: New Zealand Plant Conservation Network Alter-Natives Wikipedia Glossary of Botanical Terms
Useful words for talking about hairs or hairiness of plants.
acicular: needle-shaped
appressed: lying closely and flatly against the plant's surface
arachnoid: cobwebby
canescent: gray-hairy and hoary
capillary: very slender or hairlike
cespitose: matted or growing in little dense clumps
ciliate: fringed with hairs on the margin
clavate: club-shaped (big at one end)
downy: with very short, weak, soft hairs
echinate: with stout, blunt prickles
ensiform: sword-shaped
glabrous: without hairs
hirsute: with rough hairs
hirtellous: like hirsute but with smaller or more diffuse hairs
hispid: with stiff, bristly hairs
hispidulous: like hispid but with smaller or more diffuse hairs
hoary: closely covered with a white or whitish hairiness
indumentum: a heavy covering or hairiness
lanuginose: woolly or cottony
lanulose: wooly with very short hairs
mucro: a short and abruptly sharp or spiny tip
mucronate: ending with a mucro
pilose: shaggy with soft hairs
plumose: feathery, like the pappus hairs of some composites
puberulent: like pubescent but with smaller hairs
pubescent: downy with short, soft hairs
recurved: bent or curved downward or backward
retrorse: bent or turned backward or downward
septate: divided into partitions
sericeous: silky
setose: covered with bristles
stellate: once or twice forked, or arms radiating from base
strigillose – minutely strigose
strigose – having straight hairs all pointing in more or less the same direction as along a margin or midrib
tomentose: densely wooly or soft-matted hairiness
tomentulose: like tomentose but less so
torulose: twisted or knobby
uncinate: hooked at the tip
velutinous: velvety with erect, straight, moderately firm hairs
villous: shaggy with long, soft, not matted hairs