giving the definition of life is very difficult,
by the Sufis defines life by "hayatun yasbutu fi syai in" the circumstances in which the soul (spirit) is located (see syarqawi ala syarhil hudhudi) original text in Arabic,
living according to the philosophy of science "as-syai al-mutaharrik bil iradah" something that can move with his will (see: Idhahul Mubham) Arabic text.
with a definition of plant philosophy not a living thing, because plants have no life (with the above definition).
may all need to examine more in the meaning of life, yours @dana-edwards is very simple, but very difficult to answer ,,
greetings and friendship