(colloquial) Clipping of 意味深長 (imishinchō).

he / distal demonstrative, something far off removed from both speaker and listener: that / boyfriend

distal demonstrative, something far off removed from both speaker and listener: that, yon / particularly, male personal third person pronoun: he / by extension from he: boyfriend

意味: a meaning, a significance, the point / 異味: strange or different flavor

a meaning; a significance; a point / meaning; definition

to mean, signify, imply

he; boyfriend

deep, profound

a word, a term / language, speech

unable to put into words