From Middle English permyssyble, from Old French permissible, from Medieval Latin permissibilis.

• (General American) IPA^(key): /pɚˈmɪsɪbl̩/
• (Received Pronunciation) IPA^(key): /pəˈmɪsɪbl̩/

• Audio (Southern England):

  (file)

• Hyphenation: per‧mis‧si‧ble

permissible (comparative more permissible, superlative most permissible)

1. permitted.

   Synonyms: acceptable, allowable, legitimate; see also Thesaurus:permissible, Thesaurus:valid

   • 1944 May and June, “Notes and News: Express Travel on Slow Lines”, in Railway Magazine, page 184:

     [...] Mr. M. N. Rollason points out that on four-track lines on which the fast lines, in the centre, are flanked by the slow lines, and running at speed is permissible on all four, the traveller can enjoy some quite exciting experiences when trains are doing a "neck-and-neck" on adjacent lines.

   • 1963 March, “The Clacton express electric multiple-units enter service”, in Modern Railways, pages 172–173:

     The units will be allowed to run up to 90 m.p.h. between Chelmsford and Colchester, but their maximum speed of 100 m.p.h. is not permissible on the G.E. line.

   • 2019 July 1, Matthew Weaver, “Futuristic sounds to make electric buses safer hit wrong note”, in The Guardian‎^[1], →ISSN, archived from the original on 16 January 2021:

     Tony Bowen, of Brigade Electronics, a firm that spent three years developing a “quiet vehicle sounder”, said permissible frequencies and modulation under the regulation make it clear that the Avas should mimic an internal combustion engine.

2. (uncommon) permissive

   Synonyms: lax, lenient; see also Thesaurus:lenient, Thesaurus:permissive

   • 2016 December, Marisa Diez-Arroyo, “Vagueness: A loanword’s good friend. The case of ‘Print’ in Spanish fashion”, in Pragmatics, page 609:

     As regards the incorporation of anglicisms and despite the efforts of the Real Academia Española (an official regulatory body which aims at the purity of the language), Spanish has usually been considered a rather permissible language.

   • 2024 July 14, Jason Slaughter, “The Secret to Japan's Great Cities” (2:27 from the start), in Not Just Bikes‎^[2]:

     Japanese zoning is specified at a national level, and while local governments do have some control over their local developments, the end result is a zoning code that is very permissible compared to most other countries.

• permissibly
• permission
• permit

• impressible