Assign a multiline output from grep into a variable [duplicate]

Question

I have a data file, named words, which is made of rows and 3 columns. First column is a german word, second is its translation and third some metadata like verb, noun, etc...

$ cat words
offen open verb
Fenster window noun
Regd shelf noun

To grab all the nouns I could use grep,

$ cat words | grep noun
Fenster window noun
Regd shelf noun

I like that output because each record in its own row. The problem comes when I am trying to store that output in a variable,

$ nouns=$(cat words | grep noun)

The output now is one line where those two records merged into one,

$ echo $nouns
Fenster window noun Regd shelf noun

How can I assign a multiline output from grep into a variable?