In A Midsummer Night's Dream, the noble characters often speak in unrhymed "iambic pentameter" (also called "blank verse"). This is considered a fancy way to talk and it helps separate upper class characters from the commoners or everyday Joes of the play. Don't let the fancy names intimidate you—it's simple once you get the hang of it. Let's start with a definition of iambic pentameter.
An "iamb" is an unaccented syllable followed by an accented one. "Penta" means "five," and "meter" refers to a regular rhythmic pattern. So "iambic pentameter" is a kind of rhythmic pattern that consist of five iambs per line. It's the most common rhythm in English poetry and sounds like five heartbeats:
da DUM, da DUM, da DUM, da DUM, da DUM
Here's an example from Theseus's speech to Hippolyta:
<span>hippOLyTA, i WOO'D thee WITH my SWORD,
and WON thy LOVE, doING thee INjurIES;</span>
<span />
Every second syllable is accented (stressed), so this is classic iambic pentameter. Since the lines have no regular rhyme scheme we call it unrhymed iambic pentameter, a.k.a. blank verse.