From BiblePortal Wikipedia

King James Dictionary [1]

ISH, a termination of English words,is, in Sax. isc. Dan.isk, G. isch and not improbably, it is the termination esque, in French, as in grotesque, It.esco, in grotesco, and the Latin termination of the inceptive verb, as in fervesco. Annexed to English adjectives, ish denotes diminutive, or a small degree of the quality as whitish, from white yellowish, from yellow.

ISH annexed to names forms a possessive adjective as in Swedish, Danish, English.

ISH annexed to common nouns forms an adjective denoting a participation of the qualities expressed by the noun as foolish, from fool roguish, from rogue brutish, from brute. This is the more common use of this termination.

International Standard Bible Encyclopedia [2]

( איש , 'ı̄sh ): In the following Hebrew proper names, a prefix meaning "man of," or, collectively, "men of": Ish-bosheth, Ishhod, Ish-tob (but the Revised Version (British and American) correctly "the men of Tob"). See also Eshbaal; Eshban; Iscariot .