Yeshivish means different things to different people, depending a lot on community. In town communities think of it very much as a style. More commonly, out of town communities use “yeshivish” and frumkeit interchangeably. However, both in and out of town will use the term yeshivish to mean both level of frumkeit and style.
In Town yeshivish is a combination of external factors. Facial hair, payot, white shirt, zizit out, speaking English with a lot of Aramaic or yiddish (known as “Yinglish”), black pants or suit etc. It is also more subtle than this, you really gotta see it to know it. There personality traits that often are found among the “yeshivish” (especially the “ultra yeshivish”).
If you have all the signs you become very yeshivish. If you have some, like a beard and zizit out but a non white shirt you might be a little yeshivish or if you got the white shirt, zizit, a little shprach but a clean shave you may be average yeshivish. If you have no facial hair, a color shirt and a decent command of English there is no way you can be yeshivish even if you happen to be more serious about Judaism than the ultra yeshivish guy.
In Out of Town Yeshivish, although the above is true, there is a bigger dageish on internals. A guy who shteigs might be described as yeshivish even if he doesn’t have the signs However, a guy who is ultra yeshivish in the in town way, will certainly be yeshivish out of town.
Also, often, the less religious a person is, the more likely that person will consider someone else “yeshivish” by smaller signs. In other words, once they see, say the zizit out (or any other sign), in their minds this guy is yeshivish. It works the other way too. An Ultra Yeshivish guy will consider someone modern much quicker than an average yeshivish guy.
Whenever it’s used, you need to figure out whats meant. Especially with shiduchim. You often have no idea until you meet the guy and get to know him a little, to understand what yeshivish meant in his situation.
It’s a bit similar regarding “Modern”. Sometimes it refers to Modern Orthodox, i.e. the whole shitta. Other times it means less frum, without any shitta. Some times it is purely externals, the most important being the yarmulke.
Of course, in truth these things are all relative, depend on community, and each persons background. One person could be “yeshivish” and moving down and another person can be “modern” and moving up. It also works the other way.
Me thinks, as the Jewish community grew with its diversity, names naturally became useful in identifying a guys religious standing. Only problem is that these are subtle, so people wont really get the picture until they meet the person. I enjoy sociology, especially in the frum velt, so this is my take. I wonder what others think.
Regarding who Hashem considers chashuv, it’s a whole ‘nother story…