The rules of commas can be slippery little rascals. I find myself undoing bad habits with my students due to poor comma rule definitions and a lack of grammar practice, almost more than teaching proper comma usage.
However, one can only go so far in telling a class what not to do without showing them what to do. And, once they have mastered proper comma use, we get to mix it all up again with words like “thus.”
Thus has multiple meanings, and how you use it determines if a comma belongs with it or not. Let’s take a look at how the word thus is used and when a comma is appropriate and when it is not.
What Does Thus Mean?
Thus is a conjunctive adverb and can be used in two different ways. Conjunctive adverbs are adverbs that function as a conjunction and a conjunction that functions as an adverb.
It can mean “in this way” or “like this”.
- She was watching the birds at the bird feeder and, while thus distracted, overlooked the time.
It can also mean the same as the words “therefore,” “consequently,” or “as a result of.”
- He failed to pay attention in class, thus failing the course.
When Should Thus be Used?
Thus is a formal word that is generally used in formal speech and writing. It is also somewhat dated and not often found in modern settings or casual speech structures. However, it does make an appearance within informal speech to highlight tone or a comedic effect.
You also probably noticed above that if you removed thus from the sentences (go ahead and do it if you haven’t already), the meaning and structure of the sentences don’t change.
When Does a Comma Belong Before or After “Thus”?
When “thus” is used to mean “like this” or “in this way,” you do not use a comma. The only time you use a comma with “thus” is when it is used to replace the words “therefore,” “consequently,” or “as a result of.”
There are multiple rules surrounding comma use depending on the placement and use of “thus.”
Rule #1: Thus In a Sentence with Two Independent Clauses
Since thus is a conjunctive adverb, it works as a coordinating conjunction to join together two complete sentences.
Coordinating conjunctions are words such as but, and, or, and so and require the use of a comma placed before them. Since thus works to replace consequently or therefore in these sentences, you need to place a semicolon before it and a comma after it.
- We had over a month of three-digit temperatures; thus, I lost many plants in my garden.
- My peach tree was loaded with flowers; thus, we had an excellent harvest.
Rule #2: Thus, at the Beginning of a Sentence
If thus is used to begin a sentence, it almost always is followed by a comma. There is no strict punctuation rule concerning an introductory thus, so be sure to follow the style guide or instructor directions for consistent writing.
- We drove all through the night. Thus, we reached our destination before the crowds and were able to relax.
Rule #3: Thus to Introduce a Gerund or Gerund Phrase
Gerund or gerund phrases are a noun form of a verb ending in -ing. Gerunds are incredibly difficult for students to understand since they associate an -ing ending at the end of a verb to be a progressive form.
Examples of gerunds include:
- Dancing is fun.
- He taught us writing.
- I prefer running.
When thus is used to replace “consequently” or “as result of” to introduce a gerund, a comma should be placed before it, but not after it.
- They traveled all winter, thus missing the large snowstorm.
- She answered the question correctly, thus ending the spelling bee.
- She worked hard in class, thus passing with a good grade.
Rule #4: When Thus Interrupts an Independent Clause
When thus interrupts an independent clause, it should be set apart by placing commas on either side of it. There is one stipulation to this, however:
If the break is a weak one, you do not need commas. But, how do you know if thus is creating a strong or weak break?
Strong Vs. Weak Interruptions Using Thus
A strong interruption requires the use of commas, but how do you know if the break is strong enough to warrant their use?
If the word “thus” provides a significant emphasis or interruption to the flow of the sentence, then you need to use commas.
- My children left the field gate unlatched, thus, making it hard to catch the escaped horses.
- The instructor failed to provide the proper exam time, thus, creating confusion within the class.
- I never received the phone call to confirm the appointment, thus, forgetting to take the day off from work.
If the break is weak, no commas are needed.
- It rained all day. The streets thus were wet.
- I left my coffee at home and was thus crabby all morning.
Rule #5: When Thus is Placed Between a Helping Verb and Main Verb
Occasionally, thus will be placed between a helping and main verb in a sentence. The use of a comma is also dependent upon the weak vs. strong break to determine its use. In this case, strong vs. weak brakes have more to do with emphasis and the importance you are placing on the word “thus.”
- The dog ran circles around the yard and was thus exhausted from her escapades.
- The mystery of Atlantis still fascinates historians. It is, thus, part of modern folklore and exploration.
When Punctuating “And Thus”
You may see thus used as part of the phrase “and thus.” To use it properly, you follow the same rules laid out above.
- The gate was left unlatched, and thus, the goats got out.
- And thus, we came to the end of our review.
- I left my coffee at home and thus I was crabby.
The Idiom: It Was Ever Thus/Twas Ever Thus
Thus doesn’t come at the end of a sentence unless used within the idiom “twas ever thus.” Twas ever thus, also written as it was ever thus, means that a certain thing has always been a certain way and always will be.
Although the phrase can be worked into a sentence, it is more often used as a stand-alone comment to state how things are.
- It was ever thus, and the strong will always survive.
- Success stories start with doing hard better. Twas ever thus.
Thus means in this way or like this, but can also serve as a replacement for therefore, consequently, or as a result of.
Do you put a comma after thus? There are many instances where you do just that to either serve as a coordinating conjunction or to define the emphasis thus adds to your sentences.
When it means “in this way,” no comma is needed. But, if you are using it to replace another word, then you follow proper grammar rules.
- Add a comma after thus when it works as a coordinating conjunction or at the beginning of a sentence.
- Add a comma before thus when introducing a gerund or a gerund phrase.
- Add a comma on either side of thus when it interrupts an independent clause as a strong break or when thus comes between a helping and main verb.