If you shot normal high contrast color slide film in the 80's or 90's, blown is a good description for overdone highlights. You overexposed it and figuratively blew it, no fixing it, like you can't fix a blown light bulb or blown gasket. Blocked up isn't so great a description for highlights on slide film. But we don't want two different words for the same mistake but on different film technologies. Digital worked most like slide film in that it was easy to overdo the highlights, so blown seems to be a good word for "you blew it by overexposing and there is nothing you can do on the computer to fix it".
I understand about slide film, and thought about that yesterday, but decided it was better to be a rebel and contradict the establishment. I don't shoot slide film anymore, but when I did I didn't have any problems with overexposing, but rather the opposite. And anybody that has scanned an underexposed slide knows what 'blocked up shadows' look like (or tried printing them on direct positive paper). It's a black hole of nothing.
Anyway, whatever the term actually means, the word 'blown' amuses me to no end. It is a highly ambiguous word, and one of those terms that don't immediately make sense, belonging in the department of 'special words I must learn to understand the technical side of photography'.
It can mean so many things: Blown - as in a device that has a fan built into it, like a lot of the heating and cooling systems in North America. Blown - as in blowing something up with explosives. I blew it - as in 'I screwed up' with no precise indication of exactly went wrong.
Merriam-Webster:
Blown:
Swollen, or 'affected with bloat'. Being out of breath.
Blow up:
1: to build up or tout to an unreasonable extent <advertisers blowing up their products>2: to rend apart, shatter, or destroy by explosion
3: to fill up with a gas (as air) <blow up a balloon>
4: to make a photographic enlargement of
5: to bring into existence by blowing of wind <it may blow up a storm>
intransitive verb
1a: explode
b: to be disrupted or destroyed (as by explosion)
c: to lose self-control; especially : to become violently angry
2: to become or come into being by or as if by blowing of wind
3a : to become filled with a gas
b : to become expanded to unreasonable proportions
Blow:
1 a of air (1) : to be in motion <a breeze blew gently> (2) : to move with speed or force <the wind was blowing>
b : to move or run quickly <the linebacker blew past the tackle>
2: to send forth a current of air or other gas <don't blow on your soup>
3a : to make a sound by or as if by blowing
b of a wind instrument : sound
4a : boast
b : to talk windily
5a : pant, gasp <the horse blew heavily>
b of a cetacean : to eject moisture-laden air from the lungs through the blowhole
6: to move or be carried by or as if by wind <just blew into town>
7a : erupt, explode
b of an electric fuse : to melt when overloaded often used with out
c of a tire : to release the contained air through a spontaneous rupture usually used with out
transitive verb
1a : to set (gas or vapor) in motion <the fan blew hot air on us>
b : to act on with a current of gas or vapor <the breeze blew my hair dry>
2a : to play or sound on (a wind instrument)
b : to play (as a note) on a wind instrument
3a : to spread by report
b past participle blowed : damn <blow the expense>
4a : to drive with a current of gas or vapor <the storm blew the boat off course>
b : to clear of contents by forcible passage of a current of air <blow your nose>
c : to project (a gesture or sound made with the mouth) by blowing <blew him a kiss>
5a : to distend with or as if with gas
b : to produce or shape by the action of blown or injected air <blowing bubbles>
6 of insects : to deposit eggs or larvae on or in
7: to shatter, burst, or destroy by explosion <blow the safe open>
8a : to put out of breath with exertion
b : to let (as a horse) pause to catch the breath
9a : to expend (as money) extravagantly
b : to treat with unusual expenditure <I'll blow you to a steak>
10: to cause (a fuse) to blow
11: to rupture by too much pressure <blow a seal>
12a : botch 1 <blew her lines>
b : to fail to keep or hold <they blew a big lead>
13: to leave hurriedly <blew town>
14: to propel with great force or speed <blew a fastball by the batter>
blow a gasket
: to become enraged
blow hot and cold
: to be favorable at one moment and adverse the next
blow off steam
: to release pent-up emotions
blow one's cool
: to lose one's composure
blow one's cover
: to reveal one's real identity
blow one's mind
: to overwhelm one with wonder or bafflement
blow one's top or blow one's stack
1: to become violently angry
2: to go crazy
blow smoke
: to speak idly, misleadingly, or boastfully
blow the whistle
: to call public or official attention to something (as a wrongdoing) kept secret usually used with on