1d

Name: 1d, English Word Data
Creator: Wiktionary
License: https://creativecommons.org/licenses/by-sa/4.0/

noun

By PlainSpell · According to Wiktionary data (CC BY-SA) · analyzed May 6, 2026

The verdict

“1d” sits in 3 confusable pairs (corpus #25,647) as a noun. The look-alike neighbours are the real trap.

#25,647
frequency rank, English: 181
“1” headwords: 3
confusable pairs

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - Abbreviation of one penny (a coin with the value of 1 pence/penny; 1/240th of a pound, in pre-decimalisation currency, never used for 'one new penny').

Visual similarity to commonly confused words

How many letter changes separate each confused pair (Levenshtein distance, normalized).

1d vs 1st

33% similar

1d vs 1v1

33% similar

1d vs 1

50% similar

Source: PlainSpell confusable corpus (Wiktionary, CC BY-SA).

Key facts for 1d
Property	Value
Headword	1d
Language	English
Part of speech	Noun
Letters	2
Frequency rank	#25,647
Misspellings tracked	0
Confusable pairs	3
Source	Wiktionary (kaikki.org)

Where “1d” sits in English frequency

Every-word frequency runs from the handful of words we use constantly (left) to the long tail used once in a blue moon (right). 1d lands here:

#25,647

#1#100#1K#10K#100K

← used constantlyrarely used →

Scale is logarithmic (each tick is 10× rarer). Source: FrequencyWords open word-frequency list.

Easy to mix with look-alikes

The spelling risk for 1d is neighbouring look-alikes ("1st", "1v1", …), not just typos; it is anoun. Frequency #25,647 among 181 “1” headwords. Gloss: "Abbreviation of one penny (a coin with the value of 1 pence/penny; 1/240th of a pound, in pre-decimalisation currency, never used for 'one new penny').".

Our edit-distance generator produced no likely misspellings for 1d, since its letter pattern doesn't lend itself to common typo substitutions. It also participates in 3 confusable-pair relationships, "1st", "1v1", "1", since the words sound or look close enough that writers reach for the wrong one mid-sentence.

Etymologically, the entry records: From 1 + d (“old penny”). The correct English form is 1d, spelled 1-D.

Definition

1
Abbreviation of one penny (a coin with the value of 1 pence/penny; 1/240th of a pound, in pre-decimalisation currency, never used for 'one new penny').

Etymology

From 1 + d (“old penny”).

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA); frequency ordering uses the FrequencyWords open word-frequency list (2018 English corpus, MIT). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "1d"?

"1d" is spelled 1-D.

What does "1d" mean?

As a noun, "1d" means: Abbreviation of one penny (a coin with the value of 1 pence/penny; 1/240th of a pound, in pre-decimalisation currency, never used for 'one new penny').

What words are commonly confused with "1d"?

"1d" is commonly confused with "1st", "1v1", "1". These words look or sound similar but have different meanings. PlainSpell provides detailed comparisons for each pair.

What is the origin of the word "1d"?

From 1 + d (“old penny”). See the full etymology section above for more details.

Is PlainSpell free to use?

Yes, PlainSpell is a completely free word reference. You can look up definitions, pronunciations, confusable pairs, homophones, and spelling corrections across 5 languages without any sign-up or subscription.

Using “1d”

The practical upshot for anyone who landed here from a spell-check.

The one correct English spelling is 1-D - every other letter order is a misspelling in standard orthography.
Don't mix it up with “1st” - see the side-by-side comparison. 1d vs 1st
Browse more English words and confusable pairs in the same reference. English words

Words at a similar English frequency

Data Source

Wiktionary (via kaikki.org), licensed under CC BY-SA & GFDL. Word ordering uses an open word-frequency list; misspelling variants are generated by edit-distance from the correct headword.