Never heard of it. I found a reference to 'decars' in the Republic of Bulgaria National Statistical Institute. "Agricultural Land Prices and Rents in Agriculture in the Republic of Bulgaria in 2014 Published on: 14.04.2015 - 11:00 The average price per one decar agricultural land in Bulgaria reached 684 BGN in 2014, which was 15.2% higher than this in 2013. The average rent price per one decar hired/leased agricultural land in 2014 reached 41 BGN, which was by 7.9% higher with comparison to 2013." But the English has several grammatical mistakes so I wouldn't trust the use of 'decar' here anyway! No, I've never heard of 'decar' and I won't be using it - even if the Bulgarians do. Is it a BULGARIAN measure of land???? FOUND IT! 1000sq metres. Apparently it is commonly used in the countries of the former Ottoman Empire. One decare (whatever that is!) is the same as 10 ares (whatever they are!!!) And the spelling is DECARE according to the agricultural source I found.