@Sunil Neurgaonkar NiFi does not support this right now, but you might look at something like putting a proxy or a load balancer in front of NiFi that can remap the URL as needed.
As Mike specified in his answer you could do that. Assuming that you are not really looking to do that for your localhost, but for a production level deployment using your company domain, you could also map URL to a subdomain, e.g. customword.mycompany.com. If you want to have another anotherword.mycompany.com that means you are pointing to a different nifi cluster. Currently, there is no segmentation of nifi instance for multiple applications, something like .../nifi/app1, /nifi/app2 ... etc.
I am going to deploy it on my server.
Let's say I have a domain mydomain.com and I have put NiFi on this server. The NiFi launches on mydomain.com/nifi but instead I want it to launch in mydomain.com/customword