How to do it...

The /usr/share/dict/ directory contains one or perhaps more dictionary files, which are text files with a list of words. We can use this list to check whether a word is a dictionary word or not:

$ ls /usr/share/dict/ 
american-english  british-english

To check whether the given word is a dictionary word, use the following script:

#!/bin/bash 
#Filename: checkword.sh 
word=$1 
grep "^$1$" /usr/share/dict/british-english -q  
if [ $? -eq 0 ]; then 
  echo $word is a dictionary word; 
else 
  echo $word is not a dictionary word; 
fi 

The usage is as follows:

$ ./checkword.sh ful 
ful is not a dictionary word 

$ ./checkword.sh fool 
fool is a dictionary word