For example,

  1. Both managers and staff benefit from the workshops designed by a psychological institute to improve relationships within the workplace.

  2. Sync Online has delivered copies of contracts to all the parties who have agreed to participate in a new venture to offer music on the Internet.

In my book's manual, to-infinitive used in 1. (to improve) is adverb, and used in 2. (to offer) is adjective. How to distinguish between adjective and adverb used as to-infinitive like these sentences?

  • 3
    I'd avoid the terms 'adverb' and 'adjective' here. The to- infinitival clause in your first example is a purpose adjunct - it gives the purpose of the design of the workshops. In the second, it is an infinitival relative clause modifying "new venture". Like many infinitival relatives, it has a modal meaning comparable to that expressed by "can or "should", cf. "... a new venture that can offer music on the Internet".
    – BillJ
    Commented Feb 17, 2018 at 9:40
  • @BillJ Why isn't it considered that "to improve" in first example modify "a psychological institute"?
    – Orient
    Commented Feb 17, 2018 at 15:00
  • Because it does not identify, or add anything to (or delimit) the meaning of the noun phrase "psychological institute". Instead, it gives the purpose of the workshops which were designed by a psychological institute in order to improve relationships ...". In very simple terms, you could think of the infinitival clause as modifying the verb "designed".
    – BillJ
    Commented Feb 17, 2018 at 16:00
  • @BillJ I still don't understand... Why don't this "institute" be considered "tool" or "form" or other nouns modified by to-infinitives in JavaLatte's answer? What is different?
    – Orient
    Commented Feb 18, 2018 at 5:13
  • 1
    @Orient The difference is only made clear from the context. There is nothing in the sentence structure that explicitly shows that this is a different use of the to- infinitive. Native speakers (and sufficiently advanced nonnative speakers) understand that it is unlikely that a psychological institute was founded for the purpose of improving relations in the workplace. What is more likely is a psychological institute that has the knowledge and skills to design workshops such that they improve relationships in the workplace.
    – Tashus
    Commented Jan 16, 2019 at 22:10

1 Answer 1


Both of these sentences use a to-infinitive to express purpose, use or capability. The only difference between them is that one applies to a verb and the other to a noun.

The verb form is quite common, for example:

I am going out to post some letters

The noun use is widely documented for abstract nouns like ability, need etc, but there is less information about its use with concrete nouns. Words like tool, company and venture can clearly be associated with a purpose:

My Swiss Army Knife has a tool to take stones out of horses' hooves

There are many other possible usages, though:

This is the form to apply for a visa.
I have some money to buy an ice cream
I need a new dress to wear at the wedding

While these sentences are examples of to-infinitives applied to nouns and verbs, the terms adverb and adjective are, as BillJ says, inappropriate and misleading.

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