No, squalid is an adjective. The noun form is squalor.
The abstract noun of squalid is squalor.
The room they were living in was squalid.
The word "squalid" is used to describe a place that is extremely dirty and disgusting. An example of a sentence that uses the word would be: Being in that squalid apartment made her skin crawl.
Squalid is the adjective for squalor:)
A lot was squalid due to lack of negligence and lack of care from the owners.
The poor young man looked squalid after suffering a tough beating.
poor
dirty is the most common antonym, squalid is correct, but it is a more extreme description.
solid stolid
The squalid conditions of the tenement caught the attention of the Department of Health officials.
Dirty, bad, low, abject, squalid, filthy, wretched, sleazy...
Harry was shocked to see the squalid conditions in which some people had to live when visiting a large developing world city.