Definitions of Mindful

From the Dictionary

mindful adj 1 : bearing in mind : aware  2 : included to be aware (Merriam-Webster's Collegiate Dictionary: Eleventh Edition)
mindful adj 1. attentive, aware, or careful (usually followed by of) "mindful of one's responsibilities" (www.dictionary.com)

From Buddhism

"Mindfulness is the gentle effort to be continuously present with experience" (Bodhipaksa on the Wild Mind Buddhist website)
"Mindfulness means paying attention in a particular way; On purpose, in the present moment, and nonjudgementally." ("Mindfulness for Beginners" by John Kabat-Zinn)
"The Pali word for 'mindfulness' is sati (in Sanskrit, smriti). Sati can also mean 'retention,' 'recollection,' or 'alertness.' Mindfulness is a whole-body-and-mind awareness of the present moment. To be mindful is to be fully present, not lost in daydreams, anticipation, indulgences, or worry." (About.com on Buddhism)

From Other Sources

"Being mindful is an idea - actually a way of being - whose time has come. Mindfulness is the innate ability we have to be present, composed, and to pause before we overreact to the challenges of our busy lives. It takes many shapes and goes by many names. Some call it being in the zone or presence or flow or situational awareness. It can develop into a way of living that brings kindness and caring into everything we do. We all have the capacity to be present, it doesn't require us to change who we are, and we can also cultivate these qualities with simple practices that are scientifically demonstrated to benefit ourselves and others." (Mindful Magazine)
"Mindfulness means maintaining a moment-by-moment awareness of our thoughts, feelings, bodily sensations, and surrounding environment." (Greater Good Science Center)
"Mindfulness is a state of active, open attention on the present. When you're mindful, you observe your thoughts and feelings from a distance, without judging them good or bad. Instead of letting your life pass you by, mindfulness means living in the moment and awakening to experience. (Psychology Today)
"Mindful awareness can be defined as paying attention to present moment experiences with openness, curiosity, and a willingness to be with what is. It is an excellent antidote to the stresses of modern times. It invites us to stop, breathe, observe, and connect with one's inner experience." (UCLA Mindful Awareness Research Center)