th

th — abbreviation

1. the written abbreviation for Thursday — the day of the week between Wednesday an

1.abbreviationA1
Definition

the written abbreviation for Thursday — the day of the week between Wednesday and Friday. Used in calendars, schedules, and informal notes.

Example

The shop is closed every th (Thursday) for cleaning and restocking.

every th (Thursday) — regular weekly schedule

Please hand in your essay by th (Thursday) at 5 pm.

by th at [time] — deadline format

Common collocations
  • Mon–th
  • th at
  • every th
  • next th
  • by th

Grammar Patterns

day ranges: Mon–th / Tues–th

Usage Note

Common in schedules, calendars, and business writing. The full spelling 'Thursday' is preferred in formal letters and official documents.

Common Mistakes

I will see you on Thurs-day.
I will see you on Thursday.
'Thurs' is a written abbreviation and is not pronounced as a word.

2. the chemical symbol (written as 'Th') for thorium — a silver-white radioactive m

2.abbreviationC1
Definition

the chemical symbol (written as 'Th') for thorium — a silver-white radioactive metal found naturally in rocks and soil. In scientific formulas and the periodic table, the symbol is always written with a capital T (Th), while informal notes sometimes use lower case (th).

Example

A student pointed to the periodic table on the laboratory wall and read Th as the symbol for thorium.

Th as the symbol for [element]

A chemist wrote the equation using the symbol Th for the thorium atom.

Common collocations
  • symbol Th
  • Th as
  • the element Th
  • Thorium (Th)

Grammar Patterns

Th + verb (in scientific writing)

the symbol Th

Usage Note

In scientific writing the chemical symbol is always capitalised as 'Th'. In less formal contexts the lower-case form 'th' is sometimes used as an abbreviation for the element name.

Common Mistakes

The formula contains th.
The formula contains Th.
The chemical symbol for thorium must be capitalised in formulas and equations.

th — noun

Word family

Synonym discussion

Sense: abbreviation/2

The symbol 'Th' and the full word 'thorium' are interchangeable in scientific writing, though the symbol is preferred in formulas and the periodic table. 'Thorium' is the full name used in running text, while 'Th' is the standard chemical symbol. 'Element 90' is another way to refer to thorium by its atomic number, but this form is rare outside of chemistry textbooks and crossword puzzles. In a sentence, you would write 'Thorium (Th) is a radioactive metal' but never 'Thorium (element 90) is a radioactive metal' in normal prose.

Th ↗thoriumelement 90

Common collocations

Nouns

Phrases

  • stands for
  • written abbreviation for

Etymology

Old EnglishLatinEnglish

'th' is not a word with its own historical origin, but a conventional abbreviation formed by taking the first and last letters of common words. 'Thurs' comes from 'Thursday', named after the Norse god Thor. 'Th' for thorium comes from the element's name, which was named after the Norse god Thor as well. 'th' for thyroid hormone is a 20th-century medical abbreviation using the first letter of each part of 'thyroid hormone'. The noun suffix '-th' (as in 'growth', 'strength') comes from Old English '-þu', a suffix that formed abstract nouns from verbs and adjectives.