What does acclimatization mean?
Acclimatization is the process by which an organism — most commonly a human being — gradually adjusts to a new climate or set of environmental conditions, such as high altitude, extreme heat, or humidity. The term is central to medicine, physiology, sports science, and mountaineering: athletes training in hot climates, trekkers ascending to altitude, and workers in extreme environments all rely on periods of acclimatization to perform safely and effectively. Beyond its scientific sense, the word is used figuratively to describe anyone settling into unfamiliar surroundings, from a new workplace to a foreign country. It carries a neutral, practical connotation and appears mostly in formal or technical writing. Related forms include the verbs acclimatize and acclimate, with the shorter American variant preferred in the United States and the longer form standard in Britain. Understanding acclimatization matters because rushing it can have real consequences, from heat exhaustion to altitude sickness.
nounThe process of adapting or becoming accustomed to a new climate, environment, or set of conditions, especially physiological adjustment to changes in temperature, altitude, or surroundings.
- Physiological or psychological adjustment of an organism to a new climate or environmental conditions, such as altitude, heat, or humidity.
- More generally, the process of becoming accustomed to any new situation, place, or set of circumstances.
"After a week of acclimatization at base camp, the climbers were ready to attempt the summit."
"The expedition built in several rest days to allow for proper acclimatization to the thin mountain air."
"New employees often need a period of acclimatization before they feel fully comfortable in the office culture."
Rarely used in the plural; the uncountable singular form is standard in almost all contexts.
"The study compared acclimatizations across different altitude profiles."
Climbers can spend weeks on acclimatization before touching a summit — skip it, and altitude sickness can strike within hours.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of acclimatization
Acclimatization derives from the French acclimater, formed from the Latin prefix ad- ('to, toward') and climat-, from Greek klima ('slope, region, climate'), which itself gave English the word climate. The verb entered English in the early nineteenth century, reflecting growing scientific interest in how European explorers and settlers adjusted to tropical and alpine environments. Its cognates include climatic and the broader family of words built on klima, all tracing back to the ancient Greek idea of a zone of the earth defined by its angle of sunlight.
Related word forms
How acclimatization is actually used
Formal to neutral register; common in scientific, medical, mountaineering, and travel writing. In American English the spelling 'acclimation' (and verb 'acclimate') is more frequent, while British English favours 'acclimatization' (and 'acclimatise'). The word applies both to biological processes and, by extension, to human adjustment to unfamiliar environments or situations.
Easily confused with acclimatization
Acclimation refers to adaptation to a single changed condition (often in laboratory settings), while acclimatization specifically implies adjustment to a natural climate or complex environmental conditions.
Adaptation is a broader term covering any change that improves fit to an environment, including evolutionary change over generations, whereas acclimatization refers to short-term individual adjustment within one lifetime.