気(げ)Seemingly, Giving appearance of, [Expresses emotions or feelings]

Both っぽい and げ describe perceived qualities, but differ in nuance. っぽい refers to innate behaviors or traits that give a certain impression. For example, 子どもっぽい ('childish') or 怒りっぽい ('quick to anger'). In contrast, げ highlights perceived emotions in others. For example, 寂しげな顔 ('a lonely-looking face').

み and げ are adjective endings that serve different roles. み turns adjectives into abstract nouns that describe a quality, e.g. '深み' ('depth') or '苦しみ' ('suffering'). げ turns adjectives or verbs into な-adjectives with the nuance of seeming to possess an emotion, e.g. '嬉しげな顔' ('a happy-seeming face') or '意味ありげな表情' ('a seemingly meaningful expression').

Both ような気がする and げ (from 気) use 気 expressions to convey subtle states or impressions, but with different nuance and usage. ような気がする follows a phrase to express a subjective hunch like 'Have a feeling that (A)', e.g. 来るような気がする 'I have a feeling they'll come.' げ attaches to emotion-related stems to describe appearance based on sensory perception, e.g. 悲しげな顔 'A face with a sorrowful air.'

ぎみ (often written in kanji as 気味) and げ both describe observable states, but differ in focus. ぎみ suggests a slight or subtle tendency, often related to physical or emotional states, e.g. 疲れ気味 ('a bit tired') or 風邪気味 ('have a bit of a cold'). げ expresses perceived emotions of others, e.g. 寂しげな顔 ('a lonely-looking face').

そうに・そうな and げ both describe appearances, but with some differences. Both can be used with adjectives like 優しそうな目 'kind-looking eyes' and 優しげな目 (same meaning), though げ is more subjective and poetic. Unlike げ, そう can also describe things that seem about to happen, e.g. 雨が降りそうな空 'a sky that looks like it's about to rain'.