[ 'sɒlstɪs ]
■ noun each of the two times in the year, respectively at midsummer and midwinter, when the sun reaches its highest or lowest point in the sky at noon, marked by the longest and shortest days.
Derivatives
solstitial adjective
Origin
ME: from OFr., from L. solstitium , from sol 'sun' + stit- , sistere 'stop, be stationary'.