Definition

Noun: A system of units historically used in pharmacy for weighing medicines and ingredients. The system is based on the grain, ounce, and pound, where an apothecaries' ounce equals 480 grains and an apothecaries' pound equals 12 ounces.

Usage

This term refers specifically to the traditional, now largely obsolete, system of mass measurement in pharmacy. - The old recipe called for two drams of the herb, measured in apothecaries' weight. - Before the metric system, pharmacists relied on apothecaries' weight to compound prescriptions.

Advanced Usage

• Historical Context: The system of apothecaries' weight was standard in English-speaking countries for pharmaceutical practice until the mid-20th century, when it was largely replaced by the avoirdupois system and later the metric system (grams and milligrams).
• Legal Definition: In some older legal and medical texts, dosages and formulas may still be defined using units from apothecaries' weight.

Variants and Related Words

• Apothecary (noun): A historical term for a person who prepared and sold medicines and drugs; a pharmacist or chemist.
• Troy Weight (noun): A similar system of units used for precious metals like gold and silver. The troy ounce is also equal to 480 grains, but the troy pound is different from the apothecaries' pound.
• Avoirdupois Weight (noun): The system of weights (ounces and pounds) commonly used today for general goods in the United States and the United Kingdom. Its ounce equals 437.5 grains.

Synonyms

• Apothecaries' measure (when referring to the broader system including liquid volumes).
• Pharmaceutical weight system.

Related Phrases

• Grains, scruples, drams: These are smaller units within the apothecaries' weight system (20 grains = 1 scruple; 3 scruples = 1 dram; 8 drams = 1 ounce).
• Apothecaries' ounce: A unit in this system, abbreviated 'oz ap' or '℥', equal to 480 grains or approximately 31.1 grams.
• Apothecaries' pound: A unit in this system, equal to 12 apothecaries' ounces or approximately 373.2 grams.

Noun

1. any weight unit used in pharmacy; an ounce is equal to 480 grains and a pound is equal to 12 ounces