Control

The verb 'to control' forms its suffixes and inflections with double '-l-', although both the base form of the verb and the corresponding noun retain the single '-l-' - 'control':

• past forms 'controlled'; present participle 'controlling';
• agent noun 'controller' (historically 'comptroller') (see below)
• the adjective controllable
  • - and such negatives as uncontrollable and uncontrolled, etc.
• The rarely used adjective 'controlless' has one '-l-' from the noun, and one from the suffix '-less'. Byron wrote in Don Juan (1819) (Canto I cxvi. 61, cited OED):

The controlless core

Of human hearts

You may also want to see AWE's page on the spelling pattern involved: -l - -ll-.

Etymological note: the first meaning of the verb 'to control' was 'to check one roll (parchment document) against a duplicate [for the purpose of auditing the accounts]'. This developed into the general sense of 'to check', for facts of any kind (a sense the Italian (controllare) and French (contrôler) equivalents still have, and hence 'to reprimand', 'to tell off'. More generally, it came to

The agent noun 'comptroller' was a written form of the word 'controller', of which it is an exact homophone (the '-p-' is silent). It was adopted historically, around the start of the 16th century, by humanists who sought to apply the 'New Learning' of the Renaissance by deriving as many English words as possible from the classical languages, Greek and Latin. In this case, they made the erroneous leap to believing that 'control' was derived from computus, the Latin for 'a calculation', or 'a count', via the French compte. In fact, it is from Latin contrā-rotulātor, via the French contre-roller: 'one who checks one copy of a roll, or document, against another', or 'auditor'. The spelling comptroller is more common in American English, where it is used for 'a senior government official in charge of financial probity'. (Garner (2000) says that comptroller "is really the same word as controller (the spelling used for the equivalent person in private business)". In Britain, where it has a strongly archaic flavour, and some countries whose administration was formed on the British model, it is used mostly by royal households, and by some Government offices. The title 'Comptroller and Auditor General' (the head of the National Audit Office) points to its essentially financial duties.