Is it possible there is a "dim" around m. 25 or so?
Often a composer (or in this case, an editor) will request that an expression marking takes place over a span of time instead of instantaneously. One such standard marking is "diminuendo," which instructs the performer to gradually get softer.
It sounds like the "inuendo" is simply the latter portion of a larger "diminuendo" marking. As such, begin getting softer at the appearance of "dim" and reach the new dynamic after the "inuendo"; in many cases, the composer will give a new dynamic marking at that point.