title_body: How many different interjections like 'aha,' 'oh' would you make up for a conlang?
upvoted_answer: This is as much a question of invented culture as it is invented language. Strictly speaking, one can devise as few or as many such interjections as one likes. Likewise, the breadth and depth of meanings, overlaps and distinctions are similarly up to the inventor.
  I'd argue that if the speakers of the invented language sense the need to distinguish &quot;aha&quot; from &quot;oh&quot;, then the discoverer of their language ought to take note! Likewise, if they divide the semantic space of &quot;aha&quot; into three distinct areas, or if they don't distinguish &quot;aha&quot; from &quot;oh&quot;, then that should also be noted.
  As for the question of which are worth making words for: that's more a matter of pragmatism. Most language inventors engage with the art out of inner joy and as an expression of fundamental creativity and generativity. Making words is almost never a problem for most language inventors! If she should discover that the speakers of the invented language have a little used interjection, a word will surely present itself!