The meaning of the word medieval-ish should be quite obvious, especially if you read Terry PRatchett books.
A modern example of medieval-ish is of course Clanranald and their idea of the right clothes to wear. For instance, we have here "Bruce's Scotland tour", which is some sort of Bruce themed tour of Scotland:
http://www.clanranald.org/cln1/duncarron/bruces-scotland-tour The photos were taken at the clan's early medieval highland clan leaders motte and bailey iron aged hill fort, apparently the typical sort of residence for a clan chieftain in the early parts of the last millenium.
Anyway, lets get onto the medieval-ish parts of it.
THe very first photograph on that page fits the description nicely, since it shows a bearded fellow (you'd never have guessed that they actually kept themselves clean shaven throughout most of the late medieval period), wearing wool, linen or calico, a maille shirt and metal gauntlets. What makes it medieval-ish is the point that the gauntlets are a bit later than Bruce, the maille shirt is one of those really old types that comes down to the elbow, which by 1314 they certainly didn't, they continued all the way down to the wrist so as not to leave any gaps. And despite being an armoured knightly type with a shield he's wearing an odd baggy sort of shirt thing under his maille shirt and his helmet isn't any kind that a knight would be seen dead in.
The next photo makes you wonder if Disney or whoever knows that clanranald have nicked their "Brave" pictures, or if clanranald think that the animation "Brave" is a documentary.
Most people seem to be wearing baggy brown or undyed sheeps wool clothing. Which actually isn't so far wrong, although the profusion of leg wraps make me wonder.
Bellow that, we have them sitting down and eating, this is where medieval-ish is obvious. The eating and drinking vessels aren't enamel mugs, but neither are they particularly accurate for 1314, which is part of the definition of medieval-ish, that it be made of medieval materials and not look like a modern item.
The middle picture shows some more clothing and such which isn't so horribly wrong, as good as re-enactment in the 1990's or so. The third photo is of the "Brave" dressed woman with bow, and two men with swords. Someone's done a good job on the shield one carries, although I'm fairly sure that such heraldic-ish birds were not used at the time of Bruce. Indeed, the combination of leather and wool and odd shaped belt pouches makes it clear that this is medieval-ish again.
Another definiting part of medieval-ish is that the items should be viewed as good for several centuries, never mind whether or not they actually are or not, and never mind the social status of the person with them. E.g. sword and shield, you're telling me that the knightly person who can afford such things will be dressed in ragged clothing (Dagging and the like is different okay) or with a sword ring on their belt (hint- they're an anachronism).
Anyway, this is the sort of thing we're up against in the re-enactment world.