This document defines common terms used by historians to describe periods of time, including replacing BC and AD with BCE and CE, and defining related terms like millennium, century, decade, nota bene, circa, and ca. It notes that a millennium is 1,000 years, a century is 100 years, a decade is 10 years, BCE stands for Before Common Era formerly known as BC, N.B. is an abbreviation for nota bene meaning "note well" or something important to note, and circa and ca. mean "around" and are used when an exact date is uncertain.

1. Historians’ and the
Words and Phrases
they use
BC, BCE, AD, CE, Circa, Ca. , Nota Bene, N.B.

3. • BC will be referred to as BCE (Before Common Era)
• AD will be referred to as CE (Common Era)
What is a Millennium ?
A Millennium is a period of a 1000 years.
So, if you were born around the year 2000, you are called a
“Millennial”

5. CENTURY
• A 100 year period is called a CENTURY

6. Decade…
• a TEN year period is called a Decade.

7. BCE = Before the Common Era
was called BC, previously

8. Nota Bene and N.B.
• Nota Bene = Note well
– But usually you’ll just see these two letters: N.B.
– So, N.B. is an abbreviation for Nota Bene.
– In the absence of a highlighter, N.B. is a way of
saying “Hey LOOK! …this is important ! ! “

9. Circa and Ca.
• Circa means “around”
• An abbreviation are the letters “Ca.”
• So, if we historians are unsure about the exact
date of an event, you may see this:
– He was born 190 BCE, ca.
– ^^^^ means “He was born around 190 BCE.