HOD meaning or full form is Head of Department.
Along with India, universities, colleges or institutions in many English-speaking countries of the world use HOD or Head of the Department to represent the head of a particular Department.
The HOD is the head of a department of their establishment whose responsibility is to manage and run the department properly.
Most of the HODs or Head of Department in India are in engineering colleges, there are the different head of department for different engineering branches running in engineering college like mechanical, electrical, computer science, civil engineering etc.
Those whose work is to look after the needs of the department as well as the students and teachers of their department

For example, assuming VIT which is a famous engineering college in Vellore Tamil Nadu, there are many other courses in college along with engineering, so for each engineering branch there is a separate HOD, means Head of Department.
HODs manage a department as well as take special classes, it has often been seen that HODs take the class of an important subject, and are able to explain students better because of their experience.
In some of the best medical courses such as MBBS and MD, the HOD class is highly recommended.
Need for HOD in institutions
For any department to function properly and smoothly, it is necessary that the responsibility of that department rests with the person with experience.
If the head of that department will have the knowledge and experience of that department, then he will be able to run that department properly, will be able to take it forward.
So that’s why any institution chooses the head of a department for any of its departments, which has a good experience of that department.
consider, a HOD is needed for the electrical branch of an engineering college, which will take a lot of necessary steps to ensure that students are better taught, teachers are better served, and the entire electrical department itself is doing very well.
That means the entire responsibility of that department will be on the head of the department of that department.
In this way, due to a good experience with a responsive head of department, that department will be able to do very well and when each department will be able to do well, then the entire establishment will be able to do well.
That is why it is necessary to have an experience of that department of at least 10 to 15 years to become Head of Department.
Other famous full forms of HOD
HOD- Head of Deligation (in military organisations)
HOD- Host on Demand ( in networking)
Nice to breff all they full farms short cuts words its very help full as thanks