(mathematics) An interval in the real line which contains one of its endpoints but not the other one: i.e., it either contains its supremum or its infimum but not both.

(humorous) Quite expensive. / (from misunderstanding) Satisfactorily cheap.

In languages that distinguish vowel length, a vowel whose length is between a short vowel and a long vowel.

(slang) Partly drunk, or, possibly in meiosis, very drunk.

(idiomatic, of a person, plan, theory, etc.) Shrewd but flawed by overthinking or excessive complexity, with a resulting tendency to be unreliable or unsuccessful.

(law, historical) A jury for the trial of a foreigner, composed equally of citizens and aliens.

(optics) A mirror that consists of an incomplete reflective coating, so that half of the incident light is reflected and the other half is transmitted.

plural of half-silvered mirror

(UK, military, historical, slang) The 50th (Queen's Own) Regiment of Foot.

(of text) Formatted so that there is one half of a blank line between each line of text