‘That’ is an enemy of the Good Writer. A sneaky fellow, ‘that’ arrives in our sentences as an oh-so-flexible friend, but most of the time he's a shapeshifting waste of space. 

What type of word is 'that'?

Words are categorised according to their function and each category is known in linguistics as a 'part of speech'. The trouble with the word 'that' is: it belongs to an unusually large number of categories.  'That' can be an article, pronoun, conjunction, adverb or adjective. If you don't believe me, you could match the sentences below to the correct part of speech. Some of you will choose to scroll down for the answers but you're only cheating yourselves:

1. Pass me that mouse

2. She worked so hard that she caught a glimpse of the glass ceiling

3. Aardvarks just aren't that friendly

4. Well, that's what Vera told me

5. That pineapple is the most picturesque I've ever seen

• article

• pronoun

• conjunction

• adverb

• adjective

Our flexible friend

Belonging to so many parts of speech makes 'that' very useful and very used. Like anything that we use a lot, we tend to stop noticing it, begin to take it for granted and cease to treat it with respect.  

J D Salinger put one 'that' in the paragraph below, from The Catcher in the Rye . I've snuck in a few more. See if you can spot the one Salinger intended. Notice the effect of removing each 'that'.

Old Sally didn't talk that much, except to rave about the Lunts, because she was that busy rubbering and being charming and that. Then, all of a sudden she saw some jerk that she knew on the other side of the lobby. Some guy in one of those very dark grey flannel suits and one of those checkered vests. Strictly Ivy League. Big deal. He was standing next to the wall, smoking himself to death and looking bored as hell. Old Sally kept saying that, "I know that boy from somewhere."

A sneaky waste of space

As an astute yet sensitive person, you subvocalise as you read and can make a case for retaining any of the 'thats' in Salinger's vandalised paragraph. The first could be ironic, the second could establish the narrator's tone of voice etc. What you cannot do, is keep them all. They contradict one another, draw attention to themselves and make for very poor writing and reading. A good writer is a minimalist. Writing means paring back to the essentials. Every word has intention. Every word has function. And if it doesn't? Delete. 

Even now, 'that' will sneak into your sentences. I recently had the challenge of relaying a client's complex message as a tweet. Having spent 10 minutes wrestling with every syntactical variant to keep within the character allocation, I realised I had overlooked an entirely superfluous 'that'. How is this possible? I believe it's because we no longer hear the word. The written equivalent of our national verbal tick: 'like', 'that' is an embarrassing habit we need to kick.  

Answers: 1. article, 2. conjunction, 3. adverb, 4. pronoun 5. adjective

Only the final 'that' belongs in Salinger's novel. The paragraph should read: 

Old Sally didn't talk much, except to rave about the Lunts, because she was busy rubbering and being charming. Then, all of a sudden she saw some jerk she knew on the other side of the lobby. Some guy in one of those very dark grey flannel suits and one of those checkered vests. Strictly Ivy League. Big deal. He was standing next to the wall, smoking himself to death and looking bored as hell. Old Sally kept saying, "I know that boy from somewhere."