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The fortis-lenis distinction is usually thought of as the voiced/voiceless distinction in consonants. This is the distinction between the initial sounds in pit- bit, to-do, few-view, sue-zoo, etc. In English, there are eight fortis-lenis pairs:

Voicing (=phonation) is of course an important aspect of this distinction; so important that generative linguists often mark the distinction with the feature [+/-voice]. But voicing is not the only feature of the distinction, and in some cases it does not figure at all. In Icelandic, for instance, both lenis and fortis stops (plosives) are unvoiced. In English, lenis stops can be half-voiced or even unvoiced at the ends of words. If we compare the stops in English, Icelandic and French, we find something like the following:

(Note in this table that the Icelandic lenis stops [p t k] are written b,d,g in spelling.)

Many languages further afield use all three of these possibilities, and some even more, adding ejectives or implosives.

Five features of the fortis/lenis distinction in R.P.

Voicing (phonation)

Voicing an important feature of the distinction in fricatives:
few-view (f - v)
face-phase (s-z)
bath - bathe (þ - ð)
and in medial plosives (= plosives with vowels on either side of them):
later - lady
super cubic


Fortis consonants are generally speaking longer than lenis consonants. This is true of them all. One of the effects of this phenomenon is that fortis consonants tend to shorten or 'clip' the sounds they follow (see clipping).


This applies to the stops (plosives) and to a lesser extent the afficates.
The fortis stops p,t,k are postaspirated (most authorities use the term "aspirated") when they occur at the beginning of stressed syllables. Examples:
pot, top, cot - pt, tp, kt
but not in:
spot, stop, Scot, where the stops do not begin the syllable.


Many RP speakers introduce a glottal stop () in front of fortis stops in medial or final postions, particularly when thes stops begin a group (or 'cluster') of consonants. This also occurs before the fortis affricate . Examples:
rucksack    /rksæk/,    stopwatch   /stpw/


All four features discussed above can be represented by the idea that fortis consonants are produced with more force than lenis ones - remember that 'fortis' and 'lenis' are Latin for 'strong' and 'weak'. Some people find this concept intuitively satisfying, but it hasn't ever really been demonstrated with any certainty. I include it for what it's worth.

The following table summarizes these five points.
"+" shows that the feature in question has relevance for the consonant-types in the heading, and "(+)" means that the feature is optional or variable). Where there is a blank, the feature does not occur for that type of consonant.

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