Definition

1. Noun:
   • The fine, soft, downy hair that covers the body of a human fetus: Lanugo is a type of hair that appears on a fetus during gestation. It is typically very fine, unpigmented, and serves a protective function, often helping to hold the vernix caseosa (a waxy coating) on the skin. This hair is normally shed before birth, typically during the third trimester or the ninth month of gestation.

Examples of Usage

• Noun:
  • The presence of lanugo is a normal part of fetal development.
  • Premature babies are often born with a noticeable covering of lanugo.

Advanced Usage

• Medical/Developmental Context: Lanugo is a standard term in obstetrics, pediatrics, and developmental biology. Its persistence after birth can sometimes be noted in premature infants or associated with certain medical conditions like anorexia nervosa, where it may reappear as a sign of the body's response to malnutrition and loss of insulating body fat.
  • The pediatrician explained that the fine hair on the newborn's shoulders was lanugo and would soon fall out.

Variants and Related Words

• Vellus hair (n): The short, fine, light-colored hair that replaces lanugo on most parts of the human body after birth. While related, vellus hair is the post-natal counterpart.
• Terminal hair (n): The longer, thicker, and often pigmented hair that grows on the scalp, eyebrows, etc., distinct from lanugo.

Synonyms

• Fetal hair: A descriptive synonym emphasizing the developmental stage.
• Down: While "down" can refer to very soft, fine hair or feathers, "lanugo" is the specific biological term for fetal hair.

Notes on Meaning

• Lanugo refers specifically to the primary hair coat of the fetus. It should not be confused with the fine hair (vellus hair) that remains on the adult body. Its primary connotation is developmental and biological.

Noun

1. the fine downy hair covering a human fetus; normally shed during the ninth month of gestation