noun, used as a suffix, na-adjective
seeming to have; appearing to be
Suffix attached to nouns to describe something that looks like it has or is that thing. Often used in literary or descriptive contexts.
彼は自信ありげに話した。
He spoke as if he had confidence.
その箱は重みありげだった。
The box looked heavy.
げ is a more general suffix meaning 'seeming' or 'appearing', while ありげ specifically includes the nuance of 'having' or 'possessing'.
そう is a common auxiliary for 'seems like' based on direct observation, while ありげ is a more literary suffix attached to nouns.
Derived from the verb ある (to be, to have) combined with the suffix げ (seeming). The exact historical development is uncertain.