cm

Everyday

1. Cm is short for centimeter, a small unit of length. A meter has 100 centimeters. tree →
2. A centimeter is about the width of your little fingernail. tree →
3. (casual) People say «c-m» or «centimetres» out loud, or «a few cm»; in a hurry «cm» may be written «cms» (wrong). tree →
4. (casual) In texts «cm» can also mean «call me», so look at the context. tree →
5. (formal) Exams and science write «cm», «cm²» (square centimetres), «cm³» (cubic centimetres) and «to the nearest centimetre». tree →

In the lessons

maths: a unit of length; cm² for area, cm³ for volume; rulers marked in cm and mm; science: measuring plants, heights of pupils; everyday life: the size of a book or a phone, how tall you are; in casual talk «grew like 3 cm», «it's a few cm too short»; in rough talk «a bloody centimetre too short, typical»; in the exam voice «a segment of length 12 cm», «correct to the nearest centimetre», «the area in cm²»

Examples

• The line is 12 cm long. tree →
• The square has sides of 5 cm. tree →
• 1 m = 100 cm. tree →
• The area is 24 square cm. tree →
• My pencil is 15 cm long. tree →
• The plant grew 3 cm in a week. tree →
• A centimeter has 10 millimeters. tree →
• She is 140 cm tall. tree →
• I grew like 3 cm since summer! tree →
• The shelf is a bloody centimetre too short for the book. tree →
• A rectangle of length 8 cm and breadth 3 cm is given. Compute its area in cm². tree →
• cm when u get home (in a text: call me). tree →

Note

A unit, not a thing counted. Trap: cm and m differ by 100; cm² is area; cm³ is volume. Write «cm» with no full stop and no s: 5 cm, not 5 cms. 1 cm = 10 mm. «breadth» in an exam means width. In a text, «cm» may mean «call me», with no number in it.