As frono pretty much said already, from the usual source - Words ending with the suffix -ish are often adjectives, but this suffix has several senses. The suffix -ish is flexibly used with a base word to denote "somewhat, somewhat prone to, or somewhat like." For example, we have ticklish, reddish-blue, stylish, childish, boyish, a waspish tongue, a foolish old woman, a coldish wind.
Not to be confused with "ish" being used differently, in things like Finnish, Danish, Scottish, etc.
And, there are "ish" words like astonish, tarnish, polish, etc. where "ish" is used in another way.
Lastly, words like fish, dish, wish, etc. are just words that end in "ish", nothing more.
But when you add the "-", apparently you can put "ish" on anything you want. As frono did with "1972-ish". Anything goes - that movie was scary-ish, I'm feeling sort of sick-ish, that dog is friendly-ish, my wallet is empty-ish, and so on. No rules with the "-".
BTW, this thread is becoming very veer-ish.
walrus