Another unusual word I owe to the "Word Watching" item in Times 2.
It means the same as isosceles – "equalled legged"– but is derived from Latin rather than Greek. The second element is from Latin crus = leg.First attested in 1650, it's now rare or obsolete and has been wholly supplanted by isosceles, which came via Latin from Greek ἰσοσκελής, which is made up of iso- (as in e.g. isobar) + skelos = leg.
Here is a nice quote, courtesy of the OED, from the famous Robert Recorde, writing in 1551.
There is also an other distinction of the names of triangles, according to their sides, whiche other be all equal..other els two sydes bee equall and the thyrd vnequall, which the Greekes call Isosceles, the Latine men æquicurio, and in english tweyleke may they be called.
Recorde was born in Tenby Pembrokeshire and wrote a series of highly influential books on mathematics, and enjoyed the unique distinction of having invented the equals sign as we know it today.