vitamin K1 \vitamin K1\ n.
one of the two K vitamins, ({C31H46O2}). It is fat-soluble
and occurs naturally as the trans isomer. Chemically it is
2-methyl-3-phytyl-1,4,-naphthoquinone.
Syn: phylloquinone, phytonadione, antihemorrhagic vitamin..
[WordNet 1.5 +PJC] vitamin K2