IPA: /ˈθɪnɪʃ/
KK: /ˈθɪnɪʃ/
Somewhat lacking in thickness or density; not very thick.
The thinnish book was easy to carry around.
Thinnish is formed from "thin" (from Old English "þynne", meaning having little thickness) and the suffix "-ish" (meaning somewhat or resembling). The word "thinnish" describes something that is somewhat thin or has a slight thinness.
Think of something that is 'somewhat thin' — 'thin' describes the lack of thickness, and '-ish' suggests a resemblance or degree.