/ reə(r); NAmE rer/ adjective ( rarer , rar·est )
1.
rare (for sb/sth to do sth) | rare (to do sth) not done, seen, happening, etc. very often :
a rare disease / occurrence / sight
It's extremely rare for it to be this hot in April.
It is rare to find such loyalty these days.
On the rare occasions when they met he hardly even dared speak to her.
It was a rare (= very great) honour to be made a fellow of the college.
2.
existing only in small numbers and therefore valuable or interesting :
a rare book / coin / stamp
a rare breed / plant
This species is extremely rare.
3.
( of meat ) cooked for only a short time so that the inside is still red
—compare well done
—see also rarity
••
WORD ORIGIN
senses 1 to 2 late Middle English (in the sense widely spaced, infrequent ): from Latin rarus .
sense 3 late 18th cent.: variant of obsolete rear half-cooked (used to refer to soft-boiled eggs, from the mid 17th to mid 19th cents).