The lawprofs said it was an offensive contact with another person, as a reasonable person defines offensive. The "reasonable person" found everywhere in legal theory implicitly consents to some level of physical contact in this world, the question is how much. It's a civil violation if done negligently, and eligible for criminal prosecution if done intentionally.
Florida law sounds a little different, just touch without consent, but implicit consent presumably raises its head again. I consulted my sister the Florida criminal defense lawyer, and she confirmed that battery can be all kinds of unusual contact - an unwanted kiss, a bite - and physical injury isn't required.
So consider a hand lightly touching someone's arm, like when Fields' hand brushed up against the garment of The Donald:
@MichelleFields you are totally delusional. I never touched you. As a matter of fact, I have never even met you.— Corey Lewandowski (@CLewandowski_) March 11, 2016