Other forms: intensities
Intensity is how strong something is. The intensity of the sun at midday, the intensity of a headache, the intensity of a stare that will not drop.
Scientists use it for strength you can measure: the intensity of light, of sound, of an earthquake, of a training session. Everyday speech uses it for feeling — she plays with an intensity that is hard to watch. The adjective is intense and the adverb intensely, and intense also describes a person who is serious and burns hot about everything. The trap is time. Intensity says nothing about how long something lasts, and a pain of enormous intensity can be over in a second. For length, the word you want is duration.
1nounintensityThe strength or degree of something.
“The intensity of the wind dropped as suddenly as it had risen.”
2nounpassionGreat strength of feeling or effort.
“He argued with an intensity that silenced the whole table.”
3nounmeasurableThe measurable amount of energy in light, sound or another physical quantity.
“The meter shows the intensity of the signal in decibels.”
intensity is a measure of strength.
Intensity is built the ordinary English way: take the adjective intense and add -ity, exactly as pure becomes purity and dense becomes density. Medieval Latin had already done the job once, with intensitas. That suffix has one task — it turns a quality into a thing you can name, measure and argue about.
Proto-Indo-European
*tend- — to extend, stretch
Latin
intēnsus — strained, stretched tight; intense; attentive; violent; (rare) eager, intent
Old French
intense
Middle English
intens
English
intense
English, today
intensity
Built from
From intense + -ity. Cf. also Medieval Latin intensitas. intense comes from Late Middle English intens, intense (“ardent, fervent; extreme, great, intense”), borrowed from Old French intense (modern French intense), or directly from its etymon Latin intēnsus (“strained, stretched tight; intense; attentive; violent; (rare) eager, intent”), the perfect passive participle of intendō (“to stretch out, strain”), from in- + tendō (“to extend, stretch”) (ultimately from Proto-Indo-European tend- (“to extend, stretch”)).
Etymology from Wiktionary, CC BY-SA