unadvisable

un- +‎ advisable

unadvisable (comparative more unadvisable, superlative most unadvisable)

1. Inadvisable.
   • 1941 June, C. Hamilton Ellis, Charles E. Lee, “The Welsh Highland Railway—I”, in Railway Magazine, page 251:

     No steps were taken to enforce it, as, from the financial embarrassment of the company and the uncompleted state of the line, litigation was unadvisable.

   • 1948, William Burroughs, letter, 5 Jun 1948:

     Will go back there to get it in a week or so, but may find the harvest unadvisable for reasons of security.

2. (archaic) Unwilling to take advice.
   • 1853, John Wesley, edited by John Emory, The Works of the Rev. John Wesley, Volume 1:

     Together with pride there will naturally arise an unadvisable and unconvincible spirit.

3. (archaic) Imprudent.

• "Inadvisable" is used about 10 times more frequently than "unadvisable" at COCA (US usage) and 20 times more at BNC (UK written usage).

• “unadvisable”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.