bi-, bin-, bino-, bis-
(Latin: two, twice, double, twofold; a number; it normally functions as a prefix)
This bi- is used before s, c, or a vowel. Don't confuse this bi- with another one which means "life".
All words except biennial referring to periods of time and prefixed by bi- are potentially ambiguous. Since bi- can be taken to mean either "twice each" or "every two", a word like "biweekly" can be understood as "twice each week" or "every two weeks".
biped
1. A two-footed animal.
2. Having two feet; two-footed.
A biped is in pursuit of a polyped in hopes of having a snack.
bipedal
biplane
bipod
bipolar
bipolarity
biquarterly
biracial
biradial
biscuit
bisect
To bisect is to cut into two parts.
bisected
bisection
bisectional
bisector