Once and Of old

Once adverb - At an earlier or previous time.

Of old and once are semantically related In some cases you can use "Of old" instead the word "Once" as an adjective or an adverb.

Once and of old are semantically related in old topic. Sometimes you can use "Once" instead the phrase "Of old" as an adjective or an adverb, if it concerns topics such as earlier, previously in time or order. obsolete substitute