Fortis (definition)

these are types of sounds which are made with a lot of muscle movement and forced breath. These types of sounds are usually voiceless. The term tense, when used in reference tense vs.lax, means the same thing as well. In English “p”, “t”, “f”, and “s” are some examples of fortis consonants.

References

Crystal, David (2008). A Dictionary of Linguistics and Phonetics Sixth Edition. Blackwell Publishing Ltd.

Crystal, David. A Dictionary of Linguistics and Phonetics. The language library. Oxford, UK: Blackwell, 1997.