Dictionary.com
definitions

cockle

1
[kok-uh l]
noun
  1. any bivalve mollusk of the genus Cardium, having somewhat heart-shaped, radially ribbed valves, especially C. edule, the common edible species of Europe.
  2. any of various allied or similar mollusks.
  3. cockleshell(defs 1, 2).
  4. a wrinkle; pucker: a cockle in fabric.
  5. a small, crisp candy of sugar and flour, bearing a motto.
verb (used without object), cock·led, cock·ling.
  1. to contract into wrinkles; pucker: This paper cockles easily.
  2. to rise in short, irregular waves; ripple: The waves cockled along the shore.
verb (used with object), cock·led, cock·ling.
  1. to cause to wrinkle, pucker, or ripple: The wind cockled the water.
Idioms
  1. cockles of one's heart, the depths of one's emotions or feelings: The happy family scene warmed the cockles of his heart.

Origin of cockle

1
1350–1400; Middle English cokille < Middle French coqille < Vulgar Latin *cocchīlia, Latin conchylia, plural of conchȳlium < Greek konchȳ́lion, equivalent to konchȳ́l(ē) mussel + -ion diminutive suffix; compare Old English -cocc, in sǣ-cocc literally, sea-cockle < Vulgar Latin *coccus for Latin concha conch
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for cockles of one's heart

cockle

1
noun
  1. any sand-burrowing bivalve mollusc of the family Cardiidae, esp Cardium edule (edible cockle) of Europe, typically having a rounded shell with radiating ribs
  2. any of certain similar or related molluscs
  3. short for cockleshell (def. 1)
  4. a wrinkle or puckering, as in cloth or paper
  5. a small furnace or stove
  6. cockles of one's heart one's deepest feelings (esp in the phrase warm the cockles of one's heart)
verb
  1. to contract or cause to contract into wrinkles

Word Origin for cockle

C14: from Old French coquille shell, from Latin conchӯlium shellfish, from Greek konkhulion, diminutive of konkhule mussel; see conch

cockle

2
noun
  1. any of several plants, esp the corn cockle, that grow as weeds in cornfields
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Word Origin and History for cockles of one's heart

cockle

n.1

type of mollusk, early 14c., from Old French coquille (13c.) "scallop, scallop shell; mother of pearl; a kind of hat," altered (by influence of coque "shell") from Vulgar Latin *conchilia, from Latin conchylium "mussel, shellfish," from Greek konkhylion "little shellfish," from konkhe "mussel, conch." Phrase cockles of the heart (1660s) is perhaps from similar shape, or from Latin corculum, diminutive of cor "heart."

cockle

n.2

flowering weed that grows in wheat fields, Old English coccel "darnel," used in Middle English to translate the Bible word now usually given as tares (see tare (n.1)). It is in no other Germanic language and may be from a diminutive of Latin coccus "grain, berry."

Online Etymology Dictionary, © 2010 Douglas Harper
Idioms and Phrases with cockles of one's heart

cockles of one's heart

see warm the cockles of one's heart.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.