Can grep show only words that match search pattern?

Question

Is there a way to make grep output \"words\" from files that match the search expression?

If I want to find all the instances of, say, \"th\" in a number of files, I

Answer 1

Just awk, no need combination of tools.

# awk '{for(i=1;i<=NF;i++){if($i~/^th/){print $i}}}' file
the
the
the
this
thoroughly