To dream of a lilac indicates heartache and rejection. Additionally, this dream reminds you to be wary of your environment. Things that you see and hear should not be taken at face value.... Dream Symbols and Analysis
Whether in bloom out of doors or inside a vase, these fragrant blossoms predict a broken friendship which will cause you heartache at the time but will subsequently prove to have been a blessing in disguise.
See also Flowers and Colors.... The Complete Guide to Interpreting Your Dreams