nyct (o) - [GK] - night 夜 

nyctalopia n.  夜盲症 [al=blind; ops=eyes; -ia=disease]

nyctanthous a. (花）夜开的 [anth = flower] 

nyctophobia  n. [医]黑夜恐怖 [-phobia = fear] 

octa-, octa- [GK] = eight 八 

octagon n. 八角形 [-gon= a plane figure with. . . angles]

octahedron n. 八面体 [~hedron = a solid figure with ... sides]

October n. 古罗马的八月；公历的十月 

octopus n. 章鱼属动物[pus (←pod) = foot] 

octocentennial n. 八百周年纪念日 

octosyllable n. 八个音节的词或诗句

ole(o)- [L] = oil 油

oleiferous a. 产油的 [-ferous = bearing] 

oleograph a. 石印油画 [-graph = sth. drawn] oleomargarine n. 人造黄油，代黄油（margarine n. 黄油）

oleoresin n. [化]含油树脂（resin n. 树脂）

olig(o)- [GK] = few 少，缺 

oligarch n. 寡头政治的执政者 [-arch = chief or ruler] 

oligemia n. [医]血量减少 [-emia (-aemia) = the state of blood]

oligophagous a. (动物）寡食性的 [-phagous = eating] 

oligopoly n. 少数卖主对市场控制 [pol = to sell]

omni- [L] = all 全，总 

omnificent a. 有无限创造力的[fic = to make] 

omnipotent a. 全能的；有无限权力的[pot= be able]

omniscient a. 无所不知的 [sci = to know] 

omnipresent a. 无所不在的

oo- [GK] = egg 卵

oogonium n. [生]卵原细胞 [gon = producing]

oolite n. [地]傾石；鱼卵石[-lite = stone]

oology n. 鸟卵学[-logy=the science of]