Live/Light/Libre. Lichess is pronounced 'lee-chess.'
Live because games are played and watched in real-time 24/7; light and libre for the fact that lichess is open-source and unencumbered by proprietary junk that plagues other websites.
Similarly, the source code for lichess, lila, stands for li[chess in sca]la, seeing as the bulk of lichess is written in Scala, an intuitive programming language.
Lila:
github.com/ornicar/lilaScala:
http://www.scala-lang.org/
lee-chess. The "li" stands for "libre", and uses the same pronunciation.
Li=?