Found:

modal

SYNTAX: a modal expression indicates the attitude of the speaker with respect to the truth-value of the proposition expressed. EXAMPLE: maybe, probably, possibly, may, can, etc. Modal verbs (or 'auxiliaries' because of their defective flexion) are known to allow a non-modal interpretation. Thus you may go can either mean that the speaker feels that it is possible that you will go (the so-called epistemic reading) or it can mean that you are allowed to go (the so-called root interpretation).