Often, when both items in a pair of hyphenated phrases have a common element, the first instance of that element can be elided, or omitted, without erasing the connection; the incomplete phrase is implied to have the same form as the complete one. However, as shown in these examples, it’s essential to treat the phrases, especially their hyphens, correctly:
1. “The holding pond’s collapse sent more than a billion gallons of arsenic and mercury-laden sludge into the river.”
The sludge was laden with a combination of arsenic and mercury; arsenic was not released separately from mercury-laden sludge. Because laden can serve to team up with both arsenic and mercury, it is omitted from where it might first appear; the phrase “arsenic-laden” is merely implied. A hyphen is attached to arsenic to express the elision: “The holding pond’s collapse sent more than a billion gallons of arsenic- and mercury-laden sludge into the river.”
2. “The company provides small- and medium-size businesses with service and support.”
The hyphen following small implies that “small-size” is the intended construction, but size is not appropriate in association with small: “The company provides small and medium-size businesses with service and support.”
3. “The 1-2 year old wolf is still a baby.”
The confusing adjective string before wolf is meant to express that the animal is either a 1-year-old or a 2-year-old. You can write that an animal is 1-2 years old, but here you must hyphenate the construction “(number)-year-old” to modify the noun that follows.
The correct full form of the sentence would be “The 1-year-old to 2-year-old wolf is still a baby,” but the first instance of “year-old” can be elided: “The 1- to 2-year-old wolf is still a baby.” Note the letter space following 1– — this element has no connection to to, so don’t connect them.
4. “Marc Antony was seen as Cleopatra’s drink-and-love besotted dupe.”
The trainlike coupling of “drink-and-love” makes no grammatical sense. Observers thought of Marc Antony as separately besotted by drink and love, so he was a drink-besotted dope and a love-besotted dope, or, as follows: “Marc Antony was seen as Cleopatra’s drink- and love-besotted dupe.”
5. “The difference between pre- and post-Civil War attitudes was profound.”
The elision of “Civil War” after pre- is correct, but when a prefix or suffix is attached (or implied to attach) to a proper noun or to more than one term, a sturdy en dash is called in to substitute for the little hyphen: “The difference between pre– and post–Civil War attitudes was profound.”
6. “She felt underpaid and -appreciated.”
Though use of suspensive hyphenation in the case of words with otherwise closed prefixes (“The fund was alternately over- and underfunded”) is correct, avoid applying it with closed suffixes: “She felt underpaid and underappreciated.”
7. “The box contained a stack of 3- by 5-inch cards.”
By signals that this sentence does not refer to 3-inch cards and 5-inch cards; this statement is in a separate class. When two dimensions refer to a single object, link the entire phrasal adjective together: “The box contained a stack of 3-by-5-inch cards.”