- bicameral: based on two legislative bodies
- bicentennial: occurring every 200 years
- biceps: skeletal muscle with two origins
- bicycle: a 2 wheeled vehicle without a motor
- cent: 1/100th of a dollar
- centipede: any of numerous predaceous, chiefly nocturnal arthropods constituting the class Chilopoda, having an elongated, flattened body composed of from 15 to 173 segments, each with a pair of legs, the first pair being modified into poison fangs
- century: 100 years
- decade: 10 years
- December: the 12th month
- decimal: based on the number ten
- dual: 1. of, pertaining to, or noting two. 2. composed or consisting of two people, items, parts, etc., together; twofold; double: dual ownership; dual controls on a plane. 3. having a twofold, or double, character or nature.
- dualism: division into 2, cunning, deceit, artifice, fraud
- duplicate: repeat, copy, to double
- mile: "1000 paces"
- millimeter: a unit of measure 1/1000 of a meter
- nonagenarian: person in his nineties
- nonagon: a shape with 9 sides
- octant: 1. the eighth part of a circle. 2. Mathematics. any of the eight parts into which three mutually perpendicular planes divide space. 3. an instrument having an arc of 24°, used by navigators for measuring angles up to 90°. 4. the position of one heavenly body when 45° distant from another.
- octave: the eighth of a series
- octoroon: person of one-eighth black ancestry
- quadrille: square dance
- quarter: 1/4
- quintet: any set or group of five persons or things
- quintuplets: five offspring born at once
- September: the ninth month
- septennial: occurring every seven years
- sextet: musical group of six
- sextuplets: six offspring born at once
- trinity: the state of being threefold or triple. a group of three; triad.
- triple: 3 times something
- triumvirate: government by three persons
- trivial: insignificant, ordinary, pertaining to trivia
- unanimous: of one mind; in complete agreement; agreed; characterized by or showing complete agreement: a unanimous vote
- unicorn: mythical animal with one horn
- unity: 1. the state of being one; oneness. 2. absence of diversity; unvaried or uniform character. 3 oneness of mind, feeling, etc., as among a number of persons; concord, harmony, or agreement.
- universal: worldwide; involving all, present everywhere