Rewrite each original sentence in order to make it easier to understand by non-native speakers of English. You can do so by replacing complex words with simpler synonyms (i.e. paraphrasing), deleting unimportant information (i.e. compression), and/or splitting a long complex sentence into several simpler ones. The final simplified sentences need to be grammatical, fluent, and retain the main ideas of their original counterparts without altering their meanings.

[Q]: Conjunction is a term used in positional astronomy and astrology.
[A]: Conjunction is a term used in astronomy and astrology.

[Q]: Further, the term "The Celsius or Centigrade thermometer" was again used in reference to a particular type of thermometer at least as early as 1850.
[A]: The Celsius or Centrigrade thermometer was again used to refer to a particularly type of thermometer around 1850.

[Q]: The term is generally applied to all of Morocco, Algeria, and Tunisia, but in older Arabic usage pertained only to the area of the three countries between the high ranges of the Atlas Mountains and the Mediterranean Sea.
[A]:
It is applied to all of Morocco, Algeria, and Tunisia. In older Arabic usage pertained to the area of the three countries between the high ranges of the Atlas Mountains and the Mediterranean Sea.