Indicative
The label indicative refers to the mood category associated with an ordinary statement.

The cat is chasing the mouse.
She is working in the garden.
Oil is not soluble in water.
I will be back shortly.

Indirect object

Some verbs are followed by two objects – a direct object and an indirect object. The indirect object usually refers to the person indirectly affected by the action of the verb. For example in the sentence ‘John gave Susie the books’, Susie is considered as an indirect object whereas the books is considered as a direct object.

Infinitive
A particular verb form which expresses the verbal idea in its simplest form. An infinitive does not have any marking for tense, aspect, mood or person.

In English, the infinitive is the bare form of a verb. Examples are: write, walk, run, jump, fly, read, sleep etc.

The infinitive can immediately follow a modal auxiliary verb like will or can.

I can write.
She will come.
We must go.

The impression that infinitives are forms like ‘to write’, ‘to read’ and ‘to work’ is mistaken. The ‘to’, in fact, does not form part of the infinitive at all and can readily be separated from the following infinitive by a phrase.

For example, in the sentence ‘I wish to really understand his motive’, the adverb really separates the infinitive understand from the particle ‘to’.

Inflection
The label inflection can refer to the changes in the form of a word for grammatical reasons. The noun cat, for example, has two inflected forms, cat and cats, while the verb write has five inflected forms, write, writes, writing, written and wrote.

Initialism
The label initialism refers to the practice of constructing a word by taking the initial letters of the important words in a phrase. The words constructed by initialism cannot be pronounced as a word, but must be spelled out letter by letter.

Examples are:
BBC for British Broadcasting Corporation
FBI for Federal Bureau of Investigation