Glissando
Sliding smoothly between notes (slide on guitar)
Attacca
Attach the notes (like putting an accent on each note)
Tenuto
Holding notes for their full length
Staccato
A dot placed above or below a note. Means to play it short
Slur
Curved line above or below notes. Mean to play smoothly
Harmonics
Most notable on strings (see guitar definition below)
Detache
Detached
Con sordino
With a mute (dampen the sound)