1. (

• invent ,
• contrive ,
• devise ,
• excogitate ,
• formulate ,
• forge ,

) come up with (an idea, plan, explanation, theory, or principle) after a mental effort; "excogitate a way to measure the speed of light" ;

2. (

• fabricate ,
• manufacture ,
• cook_up ,
• make_up ,
• invent ,

) concoct something artificial or untrue ;