WORDS (or, in this case, Word.)

Whenever we have cause to drive into our local hospital/medical providers complex I notice a hospital building with signage in large letters above the wide doorway: "PAVILION". I usually mutter to the husband, "Why do they call it a pavilion for goodness sake?" "Don't know" he responds. At last I've bothered to look into my wee mystery.

Pavilion, to me, indicates some kind of tent or marquee type impermanent structure with canvas walls - the kind sometimes used at weddings for housing the reception. Alternatively I recall a book by M. M. Kaye, also adapted as a movie some years ago : "The Far Pavilions". The pavilions in that case were, I think, the peaks of the Himalayas, which were to provide sanctuary.

"An epic tale of forbidden love during the British Raj. British botanist's son Ashton Pelham-Martyn is orphaned in India and raised to believe he's an Indian boy named Ashok. Anjuli is a neglected princess, condemned first to an unwanted marriage and then to suttee when her husband dies — but happiness beckons for Ash and Anjuli in the "far pavilions" of the Himalayas, away from the prejudices that have kept them apart.

Or...in Brighton, on England's south coast, there's an ornate building: The Royal Pavilion (see below)
Royal Pavilion

Eccentric, extravagant, extraordinary…
One of the most exotically beautiful buildings in the British Isles, the Royal Pavilion is the magnificent former seaside residence of King George IV. Its fantastic domes and spires make it an easily recognizable icon, to both residents and visitors to Brighton & Hove alike. The story of the Royal Pavilion includes parties, hospitals and flower shows, contains influences from China, India and France, and includes characters as diverse as fishermen, monarchs and soldiers. As a unique palace, with a fascinating history and breathtaking decorations to discover, the Royal Pavilion has also played a key role in the development of Brighton and its international reputation for over 200 years.

The Oxford Dictionary informs me: that the word's origin is Middle English (denoting a large decorated tent): from Old French pavillon, from Latin papilio(n-) butterfly or tent.

pavilion
A building or similar structure used for a specific purpose, in particular:
1.1British A building at a cricket ground or other sports ground, used for changing and taking refreshments.
1.2 A summer house or other decorative building used as a shelter in a park or large garden.
1.3 Used in the names of buildings used for theatrical or other entertainments:
‘the resort's Spa Pavilion’
1.4 A detached or semi-detached block at a hospital or other building complex:
‘the form of alternating pavilions also allows the site to be developed in depth’
1.5 A large tent with a peak and crenellated decorations, used at a show or fair.
1.6 A temporary building, stand, or other structure in which items are displayed at a trade exhibition:

So, the orignal meaning of pavilion has been expanded and modified over the centuries. The word comes up in the bible on several occasions, in its original meaning of tent, tabernacle or dwelling.

"He made darkness his secret place; his PAVILION round about him were dark waters and thick clouds of the skies. At the brightness that was before him his thick clouds passed, hail stones and coals of fire." ( Psalm 18:11-12 )

Pavilion Class is a very good and well-illustrated history of pavilions in the old meaning of the word.
Clip:

Paintings exist illustrating tents and pavilions of various shapes and sizes through several centuries and numerous countries. This class will evaluate extant illustrations to glean what information we can about the types of tents and pavilions that were used, how they may have been supported and how they were decorated. The analysis will primarily look at tents and pavilions in the late medieval and the Renaissance time periods. Earlier than that, there are few illustrations and even fewer extant items available for research.

Pavilions were used for temporary living quarters, such as by noblemen on a military campaign and courtiers following the king on progress. It is likely that only the well-to-do with a significant train of their own servants would be carrying the large loads required to assemble and furnish a large pavilion. Lower classes in the campaign or progress would use simpler structures made by draping a large fabric over some rough sticks that were likely collected onsite. While a few simple shapes will be examined, most of the discussion on structure will apply to the more complex round pavilions seen in many of the illustrations.

I love the joy of mountains Wandering free with no concerns Every day I find food for this old body There’s leisure for thinking, nothing to do Often I carry an ancient book Sometimes I climb a rock pavilion To look down a thousand foot precipice Overhead are swirling clouds A cold moon chilly cold My body feels like a flying crane.
Han Shan

For after the rain when with never a stain The pavilion of Heaven is bare, And the winds and sunbeams with their convex gleams Build up the blue dome of air, I silently laugh at my own cenotaph, And out of the caverns of rain, Like a child from the womb, like a ghost from the tomb, I arise and unbuild it again.
Percy Bysshe Shelley