Different pronunciation for words starting with en- ( /ɪn/, /en/ and /ɪˈ/ )

Question

Are there any guides to know when to pronounce as /ɪn/, /en/ and /ɪˈ/?

For e.g. enable, entertain, enforce

Answer 1

Stress often affects vowels in English

To be clear, the symbol ˈ is usually used to mark a syllable break before a primary-stressed syllable. The word enable could be pronounced as /ɪˈneɪbl̩/, but the /ɪ/ in this transcription doesn't correspond to en-, only to the first letter, E. The N is pronounced as /n/, it's just moved to the start of the following syllable because it comes before a vowel (spelled as A and pronounced as /eɪ/ here).

The vowel in en- is pronounced as /ɪ/ only in words that have no stress on the first syllable. There are many en- words of this type.

In the less common situation where the first syllable has any kind of stress (either primary stress, marked with ˈ, or secondary stress, marked with ˌ), the vowel will not be /ɪ/.

As a stressed syllable, en- is regularly pronounced with the vowel /ɛ/ (also transcribed /e/, and called "short e": this is the vowel found in the word pen). The word entertain has primary stress on the third syllable, and secondary stress on the first syllable, so the first syllable has /ɛ/. It is pronounced as /ˌɛntr̩ˈteɪn/.

But en- also has an irregular pronunciation with a third vowel quality. Ssome words spelled with en- are pronounced with /ɑn/ in imitation of the French vowel used in words spelled with en. This irregular pronunciation of en- is possible in stressed syllables (as in ˈenvelope) and also in syllables that can be seen as unstressed (such as in enˈsemble).

"Flowchart" of questions for words starting with en-

Here's a set of questions that could be used like a flowchart (with examples of specific words):

Is the E of en- in a stressed syllable?

• Yes:

  • Pronounce it as /ɛn/: ˌenterˈtain, ˈengine, ˈenvy, ˈenemy

  • OR Pronounce it as /ɛn/ or /ɑn/: ˈenvelope

  • OR Pronounce it as /ɑn/: ˌentrepreˈneur

• No: Is the N before a consonant?

  • Yes: Pronounce the en- as /ɪn/.

    enˈcamp, enˈcapsulate, enˈcircle, enˈclose, enˈcompass, enˈcourage, enˈcrypt, enˈcumber, enˈdanger, enˈdear, enˈdeavor, enˈdorse, enˈdow, enˈdure, enforce, engage, engulf, enhance, enjoy, enˈlarge, enˈlighten, enˈlist, enˈliven, enˈmesh, enˈrage, enˈrich, enˈsconce, enˈslave, enˈsnare, enˈsue, enˈtangle, enˈthral(l), enˈtice, enˈtitle, enˈtomb, enˈtrap, enˈtreat, enˈtreaty, enˈtrench, enˈvision

  • No: Pronounce the en- as /ɪˈn/, where the second syllable starts with /n/.

    eˈnable, eˈnact, eˈnamo(u)r

  • OR Pronounce the en- as /ɑn/.

Variation in unstressed syllables

Some American English speakers tend to replace /ɪ/ in fully unstressed syllables with /ə/. This has been called the "weak vowel merger". A speaker with this merger might pronounce enable as /əˈneɪbl̩/, and enforce as /ənˈfors/.

Some speakers use the unreduced vowel [ɛ] even when en- is an unstressed syllable, which would cause enable to be pronounced as /ɛˈneɪbl̩/, and enforce as /ɛnˈfors/.

You can see a similar discussion about variability in the pronunciation of words starting with ex- in the answers to this ELU question: Is there a rule for the correct pronunciation of words starting with “ex”?