kilo

Word family

• kilogram
  nounA2
• kilometer
  nounA2
• kilowatt
  nounB2
• kilobyte
  nounB1
• kilohertz
  nounB2
• kilocalorie
  nounB2
• kiloton
  nounC1

Synonym discussion

Sense: noun/1

Kilo, kilogram, gram, pound, and tonne all measure weight or mass but differ in size, formality, and regional use. Kilo is the everyday abbreviation of kilogram, extremely common in UK, Australian, and European supermarkets for buying fruit, vegetables, or meat. Kilogram is the full formal term used in science, official documents, and labelling — always prefer it in academic writing. Gram (g) is one-thousandth of a kilogram, used for lighter items like spices, letters, or jewellery. Pound (lb) is the imperial equivalent of about 0.45 kg, dominant in US food and body-weight measurements. Tonne (t) equals 1,000 kg and is reserved for heavy loads such as vehicles, building materials, or cargo. If a British shopper says 'a kilo of apples' and an American says 'two pounds of apples,' both describe a similar quantity but use their region's default unit. For scientific precision, always write kilogram (kg) rather than kilo.

Common collocations

Etymology

Kilo comes into English from French, which borrowed it from Greek khilioi meaning 'thousand.' The noun kilo (used alone) is a late 19th-century shortening of kilogram, which was formed by combining the Greek-derived prefix kilo- with gram, from French gramme. The prefix kilo- was adopted as an official SI prefix in 1795 during the French Revolution's metric system reform. The technical combining form senses (kilobyte, kilohertz, kiloton) followed as science and computing expanded in the 20th century, extending the 'thousand' idea into new domains.