So for ‘commingled', you need one ‘m' for the prefix and another for the root (i.e. “The general rule is that while the two sounds may be assimilated, the place in the word of the assimilated sound is retained, leading to a doubling of the consonants. In the case of ‘commingled', the relevant rules are: con becomes com before b,p and m con becomes co before vowels and h con becomes col, or cor before, respectively l and r and con remains con everywhere else. “Assimilation is itself an example of this (ad + simulation). It applies especially to words of Latin or partially Latin origin. He said: “Grammarians call assimilation the process by which contiguous sounds are rendered easier to pronounce by making them similar or identical.
However, Mr Terrell, who has a degree in languages from Oxford University, which he followed with a further degree in business, claims to have found the correct spelling. The term, which is a verb meaning ‘to mix or be mixed', has many variant spellings throughout the waste and recycling sector, with both the Waste & Resources Action Programme and Defra mostly using the spelling ‘co-mingled' while others, such as, favouring ‘commingled'. Atlantic Waste’s Bruce Terrell, who studied languages and Latin before undertaking a masters at Oxford, claims commingled is the definitive spelling of the termBruce Terrell, director of London-based Atlantic Paper and Community Waste, has researched the etymology of the term used to describe the collection method and concluded that the use of ‘co-mingled' is not grammatically correct.